Yeah, we booked all our domestic flights with Thai Airways:
Dec 18 - Dec 20 - Bangkok
Dec 20 - Dec 23 - Chiang Mai
Dec 23 - Dec 26 - Phuket
Dec 26 - Jan 4 - Khao Lak
Jan 4 - Jan 8 - Bangkok
I have found a lot of hotels in Phuket around 4,000 Baht a night that are a little off the beach. Not sure which is the one to go with. A nicer one would be nice, but with a 3 week trip the price is starting to snowball We weren't aware that things were 3-5X the price during "Peak Season."
I misspoke (or typed?):
Dec 18 - Dec 20 - Bangkok
Dec 20 - Dec 23 - Chiang Mai
Dec 23 - Dec 31 - Khao Lak
Dec 31 - Jan 4 - Phuket
Jan 4 - Jan 8 - Bangkok