Bermuda is absolutely lovely provided the weather co-operates. Definately see horshoe beach. Tobacco beach is beautiful as well, but it's small and can be very crowded if more than one ship is in post.
We did the glass bottom boat tour at night. It was a great trip. Bermudians understand that tourism is the source of their revenue. The captain of the boat was very knowledgeable and entertaining. If you wait and book this right at the dock you can sae about 5 dollars per person. Since you will be there for 2 days you'll be sure to make it back to the ship! Of course if you book an excursion through the cruise line you can buy your passes for the public bus/ferry on board an skip the long line at the dock.
The caves are also worth a look and a great thing to do if the weather doesn't co-operate with you.
Also, if you like to snorkel, you should check out the snorkel park right in the dockyard. It's 5 dollars to get in, but there is a truly amazing reef just off shore. You can also rent jet skis, pedal boats and floating tubes there.
Whatever you do, have fun an report back!