We went w/ Stingray City Charters in April from Grand Princess. Had a great time. We got a good rate off the internet. I actually called GC & talked to Sterlin to make the reservations with credit card. We went to 3 sites & he was very good at StingRay City w/ getting the rays & having pictures taken (either by pro who you paid later or w/ your own camera - we got some of each). He came to pick us up at the pickup point (which is across from Capt. Marvins) & dropped us off pretty much wherever you wanted, 7 mile beach, downtown or ship pick-up point. There were about 14 of us on the boat, it was not crowded at all. You could sit out front in the sun, on top in the sun or "under" in the shade. There was soda & water to drink. We brought our own gear, but no one had trouble with his gear. He told us what to look for, where to go etc. We liked it a lot & would recommend it.
Having said that, next time I think I would try a catamaran or trimaran - mainly because we saw a really big one that looked like fun and we haven't been on one for snorkeling yet. But nothing bad to say about Stingray City Charters and would use them again without hesitation (if we weren't doing a catamaran or trimaran).
Have fun - Nancy