fligs

Planing to go to Thailand in September for almost three weeks. Not so sure on the weather and quite flexible in what I want to see (broadly Bangkok, Chiang Mai, Ko Samui).

I wanted to see how the weather is once I arrive and book transportation and hotels only about four days in advance. Rather looking to book medium to luxury resorts but not sure if that matters, also would prefer to catch a first class/sleeper compartment on a train than a seat.

I have never been to Thailand but given how the country lives from tourism, there are so many options. Can I book trains and hotels a few days in advance? I would assume domestic flights should be booked more in advance.

Thanks a lot