Thailand's Domestic Airlines
Bangkok is the busiest arrival point for overseas visitors to Thailand. If you are travelling on from there to other Thai cities by air and have pre-booked in your home country then it will most likely be by Thai Airways. While not unreasonably priced you can still fly for a lot less if you use one of the low-cost carriers that service the domestic routes such as Air Asia but be aware that if departing from Bangkok then you may need to catch a shuttle to the secondary airport, Don Muang.
The quality of these services is generally good and the flights are amazing value whichever city you head to. For people wishing to connect with international flights, these airlines may also offer a more convenient schedule that will prevent you having to hang around any longer than necessary.
Advance bookings may be difficult through international travel agents but they can be made at the company websites (see links at bottom of page).
If you don't want to plan your movements ahead of time then the good news is that you can often get seats by just turning up on the day of travel though this not such a good idea in the high season or during Thai public holidays (beware - they have lot of them !).
Useful Links -
Nok Air : Thai domestic flight bookings
Air Asia : Thai domestic and International flight bookings
Bangkok Airways : Thai domestic and International flight bookings
State Railway of Thailand
For Thailand visitors on a tight budget or who maybe just have time to spare, you can travel even cheaper by using the country's road and rail transport.
The rail service runs to some major towns and cities (connections by bus will be needed for beach resorts) and can be a leisurely and comfortable way to take in the sights. The overnight train to Chiang Mai is especially recommended for comfort and value. The Orient Express its not, but if 2 people are travelling you can get an air conditioned cabin with sink, powerpoints and large comfortable bunks for a very reasonable price.
More information can be found at the State Railway of Thailand website.
Bus Travel is Available to most destinations
If travelling at the lowest cost possible is your priority then air-conditioned intercity buses are a cost-effective alternative and run between major towns and cities. They are also a way to reach the smaller villages en route.
There are both government-run and private services offering various classes of accommodation though all but small local services should be at least air-conditioned these days.
For more information visit www.busonlineticket.co.th