There are a number of terrific guides in San Pedro. Unfortunately, there are one or two (possibly more) that must be avoided. I will not mention their names.
My favorite guide for reef fishing is Juan Alamilla - Phone 2009. A great guy with good boat with two motors. As much as I like Juan, I would use a guide with a smaller boat for bone fishing. Good bone fishing guides are mentioned elsewhere on this message board.
Other interesting stuff: We like the Winnie Estelle for a day snorkeling trip with a lunch stop at Caye Calker.
Short snorkeling trips to Shark Ray Alley and Hol Chan, use Daniel Nunez at Tanisha Eco Tours - phone 2314. Daniel is the ONLY person to use for a trip to Lamani. We learned the hard way. Again, Daniel is the only person to use for a trip to Lamani! He provides a great value!