I am flying in to GC for the evening only to fly out to Tikal the next day. I would like a comfortable,reasonable hotel close to the airport, literally just to sleep. Would like reasonable but do want a good night sleep so wouldn't want to sacrifice comfort for just a few books. I guess what I'm saying is that I don't need the amenities.

Here are 2 good ones very close to the airport, breakfast and airport shuttles included in the price (ask about very early breakfasts). The 1st is a budget place, the 2nd a great value option with amazing (and much deserved) Trip Advisor reviews. Happy trails!
http://www.hoteldoslunas.com/
http://hostalvillatoscana.com/

We stayed at villa Toscana last week when we arrived in G city. It is very close to the airport and a pleasant place with good breakfast and helpful staff.
The real problem with it and with other places nearby is that there are no restaurants in the area. And although the airport is right there, you cannot go in even to the food court easily although the guards did let us enter on an earlier trip when we showed them a ticket for the next morning. The better restaurants in the airport are all in the departures section.

Villa Toscana does have an arrangement with restaurants that will deliver food but they are relatively expensive.

I just looked at the dos Lunas link provided by hopefulist and see that they offer inexpensive meals. If you want an evening meal that would probably be the better option

Another option - the hotels in Zona 10, while not right next to the airport, would offer you easy access to a couple of the best restaurants in Central America, and are only a 10-15 minute taxi ride from the airport.