The Sheraton Grande Sukhumvit in BKK is superb. In Chiang Mai you will not be disappointed with the Westin Riverside. Phuket is problematic. If you want to be near the action I suggest the Baan Sukkothai. The only Starwood property is off in the boonies far from anything. Of course Amanpuri is reputed to be the best, but it is also a self-contained resort, so it depends on your desires. I stay at a 2-star hotel called San Inn which is very cheap when I am in Phuket. Unless you require a big chain, it will be cheaper to find your own accomodations when you get there than to make them through a travel agent.