We use sites such as Sawasdee.com, asiatravel.com, latestays.com, agoda.com and have had no problems. If you're thinking of staying in one place for a month it may be worth approaching a property you like direct to see if they will cut you a deal. Serviced apartments may be worth a look at as well as they often do good monthly rates. You don't say where you fancy going or when, some great deals can be had in the low season.

Thanks Sunbear, a couple of new ones to try there.
We are intending going November/December to escape the British winter for a while and, having never been to Thailand before, we want to see a couple of places to get a feel of the country. It's more difficult if you have never been as even the scale is difficult to imagine looking at a map. Our original plan has been scaled back as we don't want to be on the move constantly either, a mistake we made last year in a tour of Kerala.We have decided to concentrate on the south.
We will probably fly to Bangkok, stay a couple of days then I have earmarked Krabi and Cha Am as two possibly destinations and we could add a third between going back to Bangkok for the last 3 or four days then home.
Haven't decided in which order or how to get there yet . Rail, plane or car hire etc.
suggestions are most welcome !
thanks Dave

As we only have breaks of two to three weeks we tend to fly between various points within Thailand and other SE Asian countries. There's a good choice of airlines including low cost carriers such as Air Asia. We enjoy Krabi, but its many years since we've been to Cha'am. We happily do three centres in a fortnight. Given a month you could consider Northern Thailand as well - a particular favourite of ours.

Thanks for the info Sunbear. We will give the north some thought ! cheers Dave