Think we will go to Latin America! Any good ideas of what to do in 3 months? Things we cannot miss to visit?

I've only been to Mexico. I would however focus on Cuba, Venezuela, Colombia and back to Mexico hehe.
You can do plenty with 3 months in Latin America
Colombia, Ecuador, Peru
Ecuador, Peru, Bolivia, Northern Chile
Peru, Bolivia, Argentina
Brazil
Venezuela, Colombia, Ecuador
Chile, Argentina, part of Brazil
Lima to Rio via the Amazon
Lima to Rio via Bolivia
Caracas to Rio
Mexico to Panama
Really I could go on and on
Eastern Europe.
Probably the world's cheapest sub-continent overall, certainly cheaper than S.America and Asia in general - and incredibly diverse.
Budget flights right across it from many countries into others, a train network that's 2nd to none, albeit one of the slowest on the planet - but that all adds to the views, plus you get a free sleep on board if you take one of the overnighters, summers that go on for months and a thousand more things to see and do.
I'd imagine that India is probably the cheapest subcontinent in the world
I'm not agreement with that 1.
Overall - Eastern Europe comes out cheaper.

The Indian subcontinent and Indonesia are the cheapest places in the world for travel. Eastern Europe!? What countries? Moldova? I seriously doubt that it's cheaper than Indo and India, just check out hostelworld etc.

I doubt eastern Europe is cheaper than SE Asia and India, where in Europe can you get your own room for $4 (Cambodia, Myanmar) or parts of Laos you can get rooms for $1-$2. Food there is cheap and I sure transport is cheaper to.
