Just MHO, but I find on all cruises that shore excursions are overpriced and most of the day is spent waiting on one thing or another. I live in a cruise port, and my friends in the shore excursion business tell me that shore excursions are not looked at by the cruise lines as a service to their customers, but as a major source of revenue to the cruise line.
We like to read up a little on the place that we are stopping, and then either rent a car or a taxi, or public transportation, and strike out on our own for a litttle adventure. If you can hook up with another couple or two on board, it can be fun as well without being part of the 40 or 80 people on the ītourī. Some people like the security of being part of the herd, but itīs not for us.
As for the specialty restaurants, reserving the day before seems to be ample time