I've dived with Silent World and with Paradise Charters. And went lobstering with Rainbow Reef.
What was cool about Silent World is that we just walked into their shop on a Sunday morning to see what they had and they got us outfitted and onto a boat within 20 minutes. That boat was about to go out with only 3 divers and was heading to Careys Ft lighthouse. That was an awesome trip.
Paradise Charters did a good job with us the first time we went out with them (and only two other divers), so we used them again on a trip a year later. This time a DM went in the water with us. Major bummer. Follow-the- leader on the reef was a drag. You're looking at the group and following along instead of looking at the reef and going where it looks interesting. Like the touristy horseback riding trips where the horses go nose to tail. When someone had to go back to the boat, the rest of us where told to circle and wait right there until the DM came back. Their boat was clean, their gear was good, the sites were great. Our only disappointment was the DM.
One of my fav places to stay is Sunset Cove. Oops, now the secret is out. It's on the bay side and is so darn cute. One of those old Keys type places. Not as cheap as Ramada, but if you like to experience something a little different than you will like it. We've stayed at Gilbert's also (Tiki Bar is loud) and also at the jumping Holiday Isle(?) on Islamorada. Avoid Travel Lodge like the plague. Not only is it a dump, but they didn't honor the price we were quoted on our reservation. We stayed that night because it was too late to do anything else, but got new digs the next day.
With Rainbow Reef, we got a little bit ticked off because we had arranged for a lobstering trip 2 days in advance and got our lobster license at KMart (because they didn't have a boat license or something), and then when we show up they've put a bunch of snorkelers on the boat. They tried to make us feel guilty about going somewhere where lobstering would be good instead of somewhere the snorkelers would enjoy. They were like "well, it's up to them" and pointing to us. We had paid extra mind you for this "lobster trip" and had bought gloves and our licenses, and heck yes it was up to us. We didn't tell them to pack a lobster trip with snorkelers. So the snorkers were disappointed and we looked like bad guys.