^I generally agree with the above info on prices and with the fact that prices are going up quickly. In the islands, you may find bar beer prices more in the range of 90-100 baht, at least in the bigger touristy spots like Patong Beach in Phuket. Bargains can always be found, however.
One thing to add as an FYI - the new international airport that services Bangkok is opening at the end of this month (Sept 28th I believe). It is a bit further away from downtown Bangkok, KSR, etc. than Don Muang (the current airport) is. The new airport is now about half-way between Pattaya and Bangkok. Keep this in mind from a taxi or bus perspective. A taxi into Bangkok from the new airport will likely be a fair bit more than what it is now. Also, they may charge additional surcharges given it is a new airport. That is pure speculation, however. I would figure in the 500 to 600 baht range to take a taxi from airport to KSR just to be safe. Hopefully by December they will have their shit in order at the new airport. I imagine it will be pretty disorganized the next couple of months. New airports are usually disasters as far as luggage getting lost, etc.
Enjoy your trip! I imagine you will be amazed (or horrified) at all the changes that have occurred in 4 years at some of the places you have visited before. Thailand is changing at an unbelievably rapid rate.