Fist -- you need at least two weeks to do Burma so I would definitely wait and do that as a separate trip. If I were you I would simply add a day or two to Kyoto and two or three days to Bangkok.

yeah, gloria, burma looks like it would need more time. in terms of kyoto, in a perfect world, that's what we would do. but to get the flights we want at the price we want, we must leave japan on the 25th. also our window to visit siem reap, again because of plane ticket availability, is pretty narrow. but perhaps we will add at least one more day onto bangkok. my wife really wants to spend a night or two at the penn or oriental.

villa santi is not that far out of town, its just that the last bit of road is dirt...doable...
just go for the regular room, the suite looks uncomfortable to us...the furniture is low to floor and not all that nice, but it had much more room in it...
maison S is also an alternative and right in town....the grand is next to villa santi resort which might be nice also...

the anantara is not worth $425...that i can say clearly...outrageous...

samui is not cheesy except in the town of chaewaeng beach...it is cheesy imo...some of the hotels are nice but the town itself is cheesy...

take a look at peace resort and baan bophut---a new place that gets raves on fodors..

then I would add a day in LP and the rest of the time in bangkok. You won't be sorry. Hire Ratt or another driver and you can then take some day trips. And enjoy the luxury of the Penn or the Oriental -- the Penn at that time of year will be much less expensive since the Oriental tends to be heavily booked with people who come every year (Europeans and Australians) and thus rarely offers discounts or upgrades.