Don't hesitate to leave early at night to Tikal (2-3am), to see the sunrise on Tikal

The campsites in the park are great. You can rent a hammock and mozzie net and string them up in shelters. Much the nicest way to sleep in the jungle. Head up to the viewpoints early and take a torch - we found a lot of scorpions on the steps that you wouldn't want to be sitting on. They scuttle if you shine your light on them.