Renting a villa or an appartment in Thailand is good alternative to hotel and it is often cheaper than staying in hotel especially if you don't travel alone.
In Thailand, there are many many dream hotels in idyllic sceneries and goods news are they cost the price of a two or three stars accomodation in Europe.
From a booking website to another, you can find the same room at very different rates. Using a price comparison engine may be useful to pay the best price.
I admit it's a bit subjective, but Thai Smile is my favorite airline for domestic flights in Thailand. Unfortunately, they are often more expensive than Nok Air, Air Asia or Thai Lion Air (and it is justified because quality and especially onboard...