We did the malaria immunization thing both times we went to Belize. Better than to get the disease, which is horrendous. BUT, some folks don't like the side effects, so if that's the case with you, skip it. Tikal is huge, parts of it quite remote and wild, other areas flooded with tourists. It just depends on how thoroughly you want to cover it. We spent just about 1/2 day there, which was not enough. But wouldn't have missed it for the world.