USA
I would go to the USA, simply because there are some great places to see, the aircraft are pretty cheap to rent, the airspace and radio etc are easy and the service is amazing at pretty much every airport that you visit!
Flying in Europe is a pain as they just aren't geared up for GA like the Americans are. Africa is a pain too because of all the people justifying their jobs and wasting your time and mainly trying to rip you off!
You should find some great deals in the USA at the moment, not from the well known JAA schools but from small flying schools and FBO's. Some friends of mine got a C152 for $54 per hour WET (plus tax)!
Florida could be a good starting point as the weather is pretty good, but it depends if you're going in the summer as there can be a lot of thunderstorms. It's also a short hop over to the Bahamas which is a great trip!
Anyway I'm rambling and now wishing I was there, so good luck in whatever you decide to do!