I recently did a trip across Thailand – Laos – Cambodia and found that Bangkok was the easiest travel hub because of the following:

- affordable flights and multiple carrier options as BKK is a large international airport

- proximity to the other two Buddhist countries

- easy entry process as US citizens get tourist visa for up to 30 days (or was it 60) without an application process.

I would suggest using kayak.com’s flight planner to check out the economics of flying from different hubs to help you with your planning. Good luck!

fly into bangkok for sure.

depends on where you end up at the end. airasia is a discounter there, you could fly from any bigger city there back to bangkok, or bus/train back to bangkok.

Would also recommend Bangkok and AirAsia flights. Cheap flights to everywhere, just came back from roundtrip.