Have been to St Thomas quite a few times and did not want to take an excursion this time. If you have never been to St Thomas and are arriving by Cruise Ship, take the aerial tram. This will give you a fabulous view from about 800-1000' of the surrounding islands and of the cruise ships below.
If you have never seen an iguana and are arriving by either Princess or Celebrity on the northern piers, you will see many of the iguanas sunning themselves along the rocks that are just off the main pier.
One this that is beautiful about St Thomas is the water colour. Of all of the ports that we visited on this trip, St Thomas has by far the best water colour.
In my opinion, of all of the ports that I have visited on my ventures to the Caribbean over the years, Bonnaire has the clearest water by a land slide.