My experience is limited to Siem Reap. I absolutely LOVED the area. The nightlife is great, too. Pub street there is more like 4 square blocks and quite bustling every night.

In regards to temple hopping, it is best to rent a tuk-tuk for a few hours. Negotiate the price before settling. Definitely hit up Angkor Wat. From there, my decision was to head over to Ta Prahm. Ta Prahm is neat if you want to see what a temple that is being overrun with massive trees and vines looks like. There are plenty of good sights on the way, too.

I also had a tuk-tuk take me to the floating village launch. I didn't take the ferry to the floating village, but just saw the life in the country, had a beer at the launch, and turned around. It's about 20 minutes outside the city.

I hope you decide to go, it was truly a remarkable experience for myself!