Intro to the Flores (FRS) Airport
The Flores airport is small, but has a fair number of car rental places and other services. Like most airports, you could get something to eat there if you arrive early for a flight out. There is a small cafe.
The airport is actually in Santa Elena and is not all that bad of a walk, being only 2 miles from Flores after turning left onto the highway. To Flores, you are likely to pay 10Q apiece for a tuktuk. Even if you plan to spend the night in Flores, you could head straight to Tikal and ask to leave your (locked) pack in one of the hotels there.
However, if you are in no rush, travel light, and would rather pay less into town, head outside the airport and after turning right, either start out walking or wait for an empty three wheeled tuk tuk to stop to give you and another a ride to your hotel (as of early 2006) for only 10 Q.
You can get a tuk tuk for your ride from the airport, but I didn't see any there picking people up. Hence, the suggestion to walk the short distance out of the airport.
If you are wondering how to get to Tikal, don't worry. Van drivers hawking rides to Tikal will meet every flight and you would need to shoulder your way past them in order to go to Flores. My experience has been that they meet every first class or better bus as well. If thinking about heading directly to Tikal, check here.