Big Al,

This is low season, don't book anything till you get there. Mainland stuff can be done on your own if you are willing to fly to muni, rent a car and stay over nite.It will be much cheaper than any of the hotels or tour operators will offer you. It's not a hassle at all. Which ruins are you interested in? Go to Tropic Air's web site for air fare from SP to Muni. Call Crystal or any other rental car place for there rates and ask for advise on hotels from the people on the board.
From Belize City to Corazol in the north takes 90 mins. From Belize City to San Ignacio in Cayo takes the same amount of time. They are totally different places and both worth visiting more than once. If you go north, go to Lamanai If you go south Xunantunich (SP) is small but awesome. If you really want to see some ruins go to Tikal, and be there at 6:00 am. Cayo has a beatiful area caled the moutains pine ridge but the road leading up there (19 miles I think is going to take about an hour. There are several really nice resorts up there but if you are not going to stay overnite I wouldn't mess with it. Have a great trip. We are going to be there on the 24th-Aug 7 if you are there when we are let's have a drink.

Have fun,

R&D