Just returned from our fourth visit to the Inn of Last Resort. I'm a diver, but my wife is a snorkeler. She's had many wonderful snorkels from the boat while I've been diving (even on a couple of drift dives!) and can highly recommend it. The dive staff has always been very attentive to both the needs and wants of the divers and the snorkelers, and the boat drivers do a good job in keeping watch for the needs of the snorkelers while the divers are under.
As for a beach, the Inn doesn't have a true beach. It does have a nice lagoon (which has some interesting snorkeling) with a pier that takes you to a nice covered cabana and sundeck about 100 feet out in the lagoon. I've spent many a late afternoon in a breeze cooled hamock in the cabana without the insect friends I've found on the beaches on Roatan. (The cabana/sundeck has been rebuilt and about doubled in size since the attached picture was taken.)
Whatever you do, enjoy your time on Roatan.