Hi,
I'm going to be in Siem-Reap for 3-4 days on the 12th. What should I see beside Angkor Wat? Or there is nothing to see and I just should go to Phenom Pen?
Thanks

You can easily fill 3 days by exploring the ruins there. It's not just one big temple- they're spread out all over the place. You will need to hire a tuk-tuk/car/moto to get out to see Kbal Spean, Phnom Kulen, Banteay Srie and Beng Mealea and seeing those alone could take up two days. The market in town is good for browsing and picking up souvenirs (be sure to bargain!) if you get tired of looking at temples!

Nothing to see? I spent a whole week at the ruins and I live for the day I go back.
WeiLong in Siem Reap

like number two we spent 7 days there. 3 days will be full and you will need to chose what you want to see. do some research and get a guide. check out guide refernces on this site. Ankor Wat is amazing!
Do some preparation first. I always recommend Dawn Rooney's book, Angkor. As othes have said, with a mere 3 or 4 days, you can't see nearly all of the dozens of accessible temples. I spent a week there and didn't see them all.
You can accomplish an amazing bit of sightseeing in 3 days. I had just 4 but planned pretty much what I wanted to see before I left, made guesthouse reservations etc, and was up at the crack of dawn every day with my moto guy waiting for me. I was able to avoid crowds and get back before sunset, just in time for cold beers! Some people prefer to sleep in till late morning, and spend the afternoon hanging around at the poolside which can eat up the better part of a day. Different strokes...

Many spend 3 days at the Temples, but if 2 days is enough for you, you might try to go to the nearby villages or a boat trip on the Tonle Sap. We organized to go to Kampong Kleang through our guide and then took a 1 hr boat trip to see life on the lake. It was great! Many tourists also go to Chong Kneas, which is a floating village closer to Siem Reap.

There are a few things I would recommend for you to visit.
Silk Farm
Land Mine Museum
Floating Village - although not Chong Kneas
You can also find other attractions in Siem Reap
here

To whom traveling to Cambodia in particular around Siem Reap area, here are the places to visit:
- Tonle Sap: 30 mn away from Siem Reap. A floating fishing village and a unique ecosystem rich with birds and other wildlife
- Phnom Kulen: 50 km from Siem Reap. A sacred mountain offering hundreds of linga stands in the river, waterfalls and pagoda at its peak
- Local markets: the old market « Phsar Chas » & « Phsar Kandale » offer many Cambodian souvenirs at a good price/average quality…
- Artisans d'Angkor-Many locations: Chantiers-Ecoles, guided tours of the workshops – stone/woodcarving, laquering and silk painting. The Angkor Silk Farm (20mn from Siem Reap) guided tours of the silk workshops. The craftsmen you can see there are trained by Artisans d’Angkor to the traditional ancestral crafts. They sell their beautiful products in the Artisans d’Angkor’s shops. Website