There was always plenty of shopping, of course, but Carnival seems to select sites where you can do a LOT of stuff -- either take shore excursions (like we did, to see ruins or play on beaches) or just wander on your own. The Western Caribbean gave us beaches, ruins, cities to look at (the only one they didn't really allow tourists to explore was Belize City... apparently it's dangerous, but they give nice guided tours).

The only place that really didn't spark much interest for me was Grand Bahama - the beach was pretty and all, but there wasn't a lot to do there.