There is really only one activity to do in and around Siem Reap, and that is visiting the temples of the Angkor Archaeological Park.  Don't worry though, this activity is well worth the trip and the temples are so extensive and so numerous, you could spend weeks visiting them and still not be able to see everything.

Here is a breakdown of the Park, Temples, Tickets, and Getting Around:
Panhandlers and Vendors
Tickets
Getting Around
Routes
Temple Recomendations
Angkor Wat
Angkor Thom / Bayon
Preah Khan
Ta Prohm
Bakheng
Other Temples

The whole Angkor Archaeological Park is a UNESCO World Heritage site, and the Cambodian government has put in a lot of work to preserve and protect this cash cow.  They are very serious about purchasing tickets.  Every time you drive onto the Angkor Archaeological Park, you must stop by the main entrance facility for guards to check your ticket, and there are additional guards posted outside every temple who check tickets as well. 

These same guards do a good job keeping vendors and panhandlers off of the actual temple grounds.  The temple grounds are clean and quiet. 

PANHANDLERS AND VENDORS
Just outside each temple, however, is usually a small city of shops and vendors which take away from the jungle atmosphere.  As soon as you step off of your vehicle, you will be surrounded by swarms of little kids looking to either sell you items you don't need, or simply looking for a hand out.  I have traveled quite extensively in third world countries, and I will say that I found this quite overwhelming.  It wasn't just the quantity of these beggars and vendors, but it was also their voracity.  Let this be a warning -- be prepared to be overrun with these panhandlers. 

Be prepared for crowds at the main sights, especially during the middle of the day.  While Angkor Wat itself is always covered with people, no matter what time of day, most of the other temples I went to (to include Angkor Thom) were absolutely empty before 8am (also primo photo-taking periods because of the light and because of the heat).

If you are looking to take good pictures of the Angkor Wat interior, I would recommend waking up for sunrise.  While there will be numerous people in the grounds taking pictures of the exterior, the interior will usually be quite empty.  There is never a time when the temple grounds are devoid of people, except maybe during heavy rains.

The temples further afield, however, are often quite empty.  Again, more people will be at these temples in the late morning and on into the afternoon.

The Angkor Archaeological Park is definitely a place that rewards those who wake up early with uncrowded (often empty) temples and cooler, more comfortable temperatures.

TICKETS
You can buy 1 day, 3 day, and 7 day tickets to the Angkor Archaeological Park.

Tickets prices are:
1 Day Pass: 20 USD
3 Day Pass: 40 USD
7 Day Pass: 60 USD

You can purchase the tickets at the entrance to the Archaeological Park between Siem Reap and Angkor Wat.  Your driver should know where to go.

Beware of anybody trying to sell you a "used pass" as these are illicit and often won't get you into the temples anyway.  You can see what my pass looked like below.  Your picture would be where the black square is on the Front of the pass.  Note that the pass has specific dates written on it.

Also note the visiting hours indicated on the back of your pass.  The temples are open from dawn to 5:30pm, and you will be asked to leave at 5:30pm even if the sun hasn't set yet.

If you arrive at 4:30pm or later, you will be able to buy a ticket for the next few days and they will still let you into the park to see the sunset (ie, if you go at 4:30pm on Sunday and buy a 3 day ticket, you will get into the park Sunday evening, and the ticket will apply Monday - Wednesday).

FRONT:


BACK:
 

GETTING AROUND
There are different ways to getting around Angkor Archaeological Park, depending on what level of comfort / convenience you're looking for, and how much you're willing to pay.

1. Foot (0 USD) - I don't even consider this to be a real option, and I certainly would not recommend it.  The heat will be quite unbearable, and the distances are not close enough to make this realistic except for the hard asses and the extremely cheap.

2. Bicycle (2-4 USD per day) - The area around Siem Reap and Angkor Wat is fairly flat, and bikes are an easy way to get around town.  But again, if you've booked a hotel close to Pub Street, you won't need a bike around town.  And the temples are a little too far (and the heat too oppressive) to bike out to them.  Another option only for the extremely cheap folks out there.

3. Motorcycle with Driver (1 USD around town, 8-10 USD per day for temples) - You can easily find folks zooming around on motorcycles who are willing to give you a ride.  Keep in mind that this may not be the best option in the rain.

4. Tuk Tuk (12-20 USD per day) - My personal choice of transportation around the Angkor Archaeological Park.  This is essentially the Cambodian version of the SE Asian staple -- motorcycle drawn wagon, with a cushioned bench seat for two people and a roof to protect against the sun and rain.  Your driver is also your guide and should be taking you to all the "best sites" for photos.  Note that further temples will probably involve additional charges. 

5. Taxi (25-30 USD per day) - Certainly the most comfortable (and most expensive) way to travel.  Most taxis have air conditioning, which provides a welcome respite from the heat.  This mode is probably best reserved for the faraway temples (which will increase the price two-fold) like Beng Mealea or Phnom Kulen which are up to 100 km away.  Any ride over that distance (remember, it will be two ways as well, so now we're talking up to 200 km) in a tuk tuk will prove to be quite uncomfortable.


ROUTES
There are two typical routes that drivers take you on through the Angkor Archaeological Park: The Grand Circuit and the Small Circuit.  The Small Circuit provides a taste for those in town for only one or two days.  The Grand Circuit is for those in town for at least three days.  Keep in mind that you can make your own route as well.

The Small Circuit Begins at Angkor Wat and loops up to Angkor Thom, Ta Prohm, and Banteay Kdei.  It also includes some minor temples such as the Baphoun, The Terrace of the Leper King, the Terrace of the Elephants, the Twelve Prasat, Spean Thma, an Sras Srang.  The circuit ends at Angkor Wat.

The Grand Circuit extends past the Small Circuit to Preah Kahn, Preah Neak Pean, Ta Som, and Preah Rup.  The Grand Circuit in total will hit all the main sites besides the further out Banteay Srei and Roulos Group.


TEMPLES
Everyone has a different favorite temple or their own "short list" of must-see sights in Angkor.  My top four would have to be Angkor Wat, Angkor Thom, Ta Prohm, and Preah Khan.  The first two are of course the most well known sites, and are also the grandest. 

Most guidebooks will recommend that you catch a sunrise at each location, and a sunset at Angkor Wat.  I recommend these as well -- the colors are truly remarkable at both locations and waking up early or staying late will ensure light crowds (especially at Angkor Thom -- it is deserted before 8am because everyone is catching the sunrise at Angkor Wat).

Many guidebooks also recommend a sunset at Bakheng, a pyramid-like temple on a hill overlooking Angkor Wat.  While Bakheng certainly does have nice views overlooking Angkor Wat (you can see how it is positioned in the jungle), I would not rate this temple, or even the sunset experience in my top four. 

I loved Ta Prohm and Preah Khan because of their out-of-the-jungle "Tomb Raider" type feel.  They have been overgrown with ficus trees, and you will find yourself scrambling over rocks as you explore these sites.  Ta Prohm is very well known, and thus very crowded, which certainly takes away from the solitude.  Preah Khan, however, has much fewer visitors.

Angkor Wat:
Everyone's favorite temple, and certainly the most majestic (and the most crowded).  Angkor Wat is the centerpiece of any trip to the Angkor Archaeological Park.  I recommend you see both a sunrise and a sunset from here.  For additional photos of Angkor Wat, check out our Angkor Wat gallery.

Angkor Thom & Bayon:
Angkor Thom is another "must see" for any visitor to Cambodia.  The 54 towers of the Bayon, with their four faces on each tower, are one of the most memorable parts of any trip to Angkor.  Angkor Thom's grounds are quite extensive, and include a number of smaller temple sites such as the Elephant Terrace and the Terrace of the Leper King.  For additional photos of Angkor Thom & Bayon, check out our Angkor Thom gallery.

Ta Prohm:
Is a very popular site because the trees have been left growing out of the stonework.  This gives the site the feeling of it having just been discovered, and the mixture of nature and human architecture is simply stunning.  For additional photos of Ta Prohm, check our our Ta Prohm gallery.

Preah Khan:
Preah Khan is another top site that offers overgrown temples and "Tomb Raider" type pictures without the crowds of Ta Prohm.  The grounds are quite extensive and you will get the true feeling of being an explorer as you clamber over rocks and down passageways that suddenly end.  For additional photos of Preah Khan, check out our Preah Khan gallery.

Bakheng:
This five-terraced pyramid was built in the the mountain-temple style of the 9th Century, two hundred years before Angkor Wat.  The top of the pyramic offers views over the jungle and Angkor Wat far below.  Guidebooks recommend this hilltop temple as the perfecgt site to catch a sunrise or sunset, but I found it a little bit lacking and not entirely worth the trek up.  Locals do offer elephant rides up the mountain.  For additional photos of Bakheng, check out our Bakheng gallery.

OTHER TEMPLES

Ta Som:

Banteay Kdei:

Neak Pean: