Thailand, Thailand, Thailand.

Your question was a little vague in some of the other parameters as far as budget and such, but Thailand I have always felt is a great vacation spot. It has everything for everybody. You can also split it up if beaches and relaxing are not the only thing you want to do, hit Bangkok for a little bit before or after the relaxing.

You will have to get creative on your routing, but you have found the right people to help you out on maximizing your travel.