Hi Khun Pamela,
My 5 cents. Although the price of the tour you suggested sounds OK I'd do it on my own if I were you. Gives you a lot more freedom to do what you want and would probably work out cheaper. It isn't difficult especially for a seasoned traveller like yourself. Fly BKK PP on Air Asia (book ASAP to get the best rates) and take the bus or hire a taxi between Phnom Penh and Siem Reap. It's dead easy to get tours once you're there, hiring a tuk tuk with an English speaking guide (well my tuk tuk driver doubled as the guide) to see Angkhor Wat and the temples cost $10/day when I was there 3 years ago, doubt if it's increased too much. Or you can rent a bicyle. The entrance fee to visit the temples was $40 for a 3 day pass or $20 for a one day pass and you need a photo for the pass.
Have a look at this hotel for Siem Reap ... I didn't actually stay there but used the pool a couple of times and it's very pleasant... as Scotters said, a pool is good after the temples.
Bopha-Angkor.com - 
to Bopha Angkor Hotel & Restaurant - Siem Reap, Cambodia
PS. Please take pics of the fried spiders en route between Siem Reap and Phnom Penh for Mark as my digital camera was in repair when I went (green mould problem again) and I only had a throw away camera from a 7/11 with me.
