I do NOT recommend a day trip to Tikal. You will spend most of your time waiting to get there, getting there, and getting back. The plane is often late, the Guatemalan government not necessarily cooperative, and two or three hours of time actually in Tikal is simply not able to do it justice. If you can't spend at least overnight, my advice is to instead take a day trip to Lamanai, or some other day trip within Belize to see one of the Belizean ruins.
If you do take a two or three day trip to Tikal, do not let them sell you a complete "package" the food at the hotels there is pretty awful and expensive, whereas there are a couple of delightful and inexpensive restaurants right outside the park. The "packages" the travel agents sell are overpriced. You can save on using one of the many vans parked at the airport in Flores waiting for tourists at half the price that the "package" will offer you. Buy your air and hotel room in advance (to make sure you have them) but everything else should be purchased when you get there.)
Susan Guberman-Garcia, Attorney at Law. Phone: 510-792-2639
Fax/Voicemail:: 510-405-2016 Email: firstname.lastname@example.org