Most visitors to the Mayan ruins of Tikal come for the day and then leave...My wife and I were able to spend the night nearby; the next morning, we woke up early enough to beat the crowds; we felt as if Tikal had become 'our' jungle, 'our' pyramids. We marveled at the toucans flying overhead--they really look like flying bananas, with black bodies attached!...parrots, weaverbirds...and the otherworldly howler monkeys in the still cool canopy. Few places in Central America are as photographed as Tikal, but if you have time to wander the ancient city alone, it still feels newly discovered.
If you can possibly swing it, try and stay the night. (There's only one hotel on the Park grounds, so book early.)