Are you staying on the beach or close to it? We went a few years ago for our wedding anniversary. We did the 7 day cruise around the islands and flew in a couple days early just to get over the jet lag and do touristy stuff in the area.
We stayed at a hotel a few blocks away from the beach. We both are big walkers so we walked everywhere. Our trip was in December so it was a great break from the cold at home. I'm not sure what the weather is like in July.