Emerald Coast Sailing in Pensacola: http://www.ecsailing.com/
Relatively small fleet - limited choices for 6. I checked out their boats a few years ago and they appeared to be in very good shape. we went with Nautica (below) because their rates were a lot lower at the time and we were particularly price sensitive because it was a Boy Scout cruise.

Nautica Charters at The Grand Hotel, Pt. Clear, Mobile Bay: http://www.nauticaltd.com/
Very small operation & fleet, only a few boats when we chartered from them a couple of years ago. Boats were in good shape. No big issues with charter.

Pensacola Yacht Charters: http://www.pensacolayachtcharters.com/
Never used them and looks like another small operation.

I've sailed the northern Gulf Coast for years in my own boat and know the area between Alabama and Panama City pretty well if you have any questions.