i would do lots of research before you book, I have been to Thailand 7 times now and found the prices between tour operators vary greatly.
I have used Tradewinds, Kuoni and Thomson Tailormade in the past and all have been great.
I have also done D I Y , i would study brochures a bit , decide where you want to go and when then try them all, THG are very good value as a tour operator, let us know how you get on, love shirleyv.

I've done DIY, mixed and matched with tour ops and sole sourced from one tour op. To be honest there is no hard and fast rule as which way will offer best value. I do DIY as I prefer the total flexibility it gives me and access to hotels and resorts in Thailand that may not be in the brochures.

I've used Cosmos, Silverbird, Premier, Hayes and Jarvis, BA Holidays, Gold Medal, Kuoni, Colours of Asia among others. Many use the same ground handling agents so what you are getting is pretty much the same product. I have to say Premier Holidays did stand out from the ones I've used as they used to get some good deals regarding upgrades and free nights.

Thailand is a very easy country to diy, but maybe a little hand holding on your first trip by using a tour op might be reassuring.

Thanks for that, I'll have a general look around first before deciding.

We've used Colours of Asia, Travel Bag, Travel Mood and Kuoni before to pick and mix what we wanted

Most hotels have a book of tours you can choose from, just ask at reception then they will book them for you.