Southeast Asia forum

Hi--still trying to hammer out the details of approximately 3 week itinerary in SE Asia. We really want to see as much as possible while there but we're also wary of exhausting ourselves. We're planing on using a Bangkok Airways Discovery Pass to fly and save time where possible. Here's one option we came up with--is this doable? Should we cut out one place? If so, which? Any advice would be greatly appreciated thanks!

6/12-Arrrive BKK 9 pm (after 23 hrs of travel!)
6/15-Fly to Chaing Mai
6/17-Fly to Siem Reap via BKK
6/19-Fly to Luang Prabang
6/23-Bus to Vang Vieng
6/26-Back to BKK via bus to Vientiane to Udon Thani to flight to BKK
6/27-Fly to Ko Samui
6/30-Fly back to BKK
7/1-Early morning flight back to NYC