Hi there, We just got back from A/C and Tikal (31 dec, 2000).
What I would suggest if you want to see ruins (that was our main goal) is to plan on 4-5 days in Flores, Guatemala. From there they have lists of tours that you can take. And it's a 7.x to 1 US dollar exchange. nice and inexpensive.
You do have to pay a 30 USD departure tax for leaving Guatamala and 20 USD for leaving Belize, so, try to leave each only once.
I have a town map of Flores at work, email me at [email protected]
if you want some hotel numbers.
Flores is an island, very small, and clean.
We likes Flores more than anything else on our trip. Which was a BIG surprise!