I have a disability also so I can't snorkel although I would love to. We visited St Thomas about three weeks ago and we took a tour with Godfrey. It was amazing. He picks you up at the ship and takes you downtown shopping for a couple of hours (in my case I became tired and went back to where he was parked. There was a little park where I could sit on a bench under the trees and wait for everyone to return.) He then took us on a two hour tour of the island. For those who wanted to go to the beach, we took them there (they had their choice of which beach to go to) and we got off the bus to have a 10 minute look around. He then took us back to the ship. If you were at the beach, he went back and got you about two hours later. All this for $20 per person.
He was great
Let me know if you want to see pictures.. I can email them to you.