I did it in May thru Captain Marvin's. It included the turtle farm, Hell, 7 mile beach (photo stop), and the rum place. On the way back, we had the choice of returning to the tender pier or to the beach...so if you were planning a beach afternoon it would save you the transportation one way. We paid $30 per adult, which is actually the cost of the admission to the turtle farm alone if booked thru Boatswain's (the place that runs the turtle farm.)
Worth it....Hell is grossly over rated. It is a land formation, souvenier shops, and post office. Worth seeing for all of 5 minutes. The turtle farm was totally wonderful. We had plenty of time there for photos, holding turtles, etc. Our guide for the tour was great--lots of commentary, island history, etc. He tried to catch an iguana for us, and had to stop the vehicle to chase one off the road so he didn't hit it. We could have had as many samples of rum and rum cake as we wanted....and if you have teens involved, no one asked about ages.
Truly, I think young kids would have been bored with all but the turtle farm. It took about 2 1/2 hours total. I thought it was worth the money. As I said, adult admission to the turtle farm is $30, and then you still need to pay for transportation. We got the whole tour for $30.
Captain Marvin's is very easy to do. WHen you exit the tender pier area you cross the street and head to the left about 1 block. You can see it from the street as you exit the pier. If you don't see it, ask anyone where the Dairy Queen is--Captain Marvin's is 2 "stores" closer to you than the DQ, but EVERYONE seems to know where the DQ is!