We have our flights booked RT from the US in December. Once in Bangkok, we need to fly to Luang Prabang, then to Chiang Mai, then to Koh Samui, then back to Bangkok. (We might flip the Chiang Mai/Koh Samui part of the trip.)

What is the recommended approach for booking the tickets? Four separate tickets? All segments on one ticket even though they're not on the same airline? Some other split? If booked on one ticket, recommended carrier to book with initially?

TIA!