Picking up a tour at the port

We are a group of 6 seniors who are not interested in stingrays, turtles or snorkeling trips, but would enjoy a half day tour of the island and possibly some beach time. Will there be tour vendors at the port or would it be better to book something ahead of time? We haven't seen anything that appeals to us online. We have had good luck booking tours at the port at several other ports. Suggestions appreciated!

For my tastes, the island above water isn't that attractive (below water is where the true beauty lies). If I only had a half day, I would use the public buses to explore the different parts of Seven Mile Beach - lunch at either Hemingways or Royal Palms, and beach time at either of those two places or Public Beach/Calico Jack's, then maybe Cemetery Beach. It's a really nice beach and the water is calm and warm. If you want lunch off the beaten path, get the bus up to Macabuca which is a tiki bar where you can sit by the water.

That's a fantastic way to get a "taste" of GC. The bus is easy, cheap and reliable!