What do you wanna go for? Adventure? relaxation? culture?
If you want adventure/backpacking then I'd recommend South-East Asia, specifically Cambodia. It's amazing, and being a Tomb Raider fan I quite enjoyed jumping around the old ruins of the Khmer empire. They've a ton near Siem Reap that are in the middle of the jungle. Quite an experience. It also has nice beaches as does Thailand. The Thai are a bit wiser to tourism though (they'll see you as a walking ATM).
Culture I'd recommend either Egypt, Greece or Italy. Lot's of very cool anchient history. I've also heard great things about Mexico and Peru which is a bit nearer the States and probably cheaper for you?
Relaxation, probably Southern Spain... although it'd probably have more British people than Spanish, lol.
And if you want to go to the future, you might want to visit Japan ;)