If you're travelling the world....you should go everywhere! :P Just kidding. But yeah, Europe, Central America, and some parts of Asia would be my top choices.
I've been on a few vacations to Costa Rica, Jamaica and the Dominican Rebublic, and I would say Costa Rica is still my most memorable vacation. It was beautiful there and I did so many things in such a short amount of time.
I haven't been all over Europe, but I have been Germany a few times to visit a friend who lives there, its a very nice country, but I probably wouldn't go there if it weren't for the friend. I also travelled around with her visiting her family in various smaller countries like Austria, Serbia and Croatia, and that was a far more memorable experience, it wasn't like the luxury resorts I was used to on my vacations, it was much more interesting because I got to spend time with people who lived there and immerse myself in their culture.
I've also always wanted to go to Japan, Italy, Ireland, and England. So those are my recommendations based on my personal preferences and experiences. Have fun!
