We've been cruising for 36 years, and the only time we take a ship excursion is if we have OBC to burn. We've taken trains all across Italy; hopped on a train in Germany and just rode west for several hours, getting off when we saw something interesting; rented a car in Argentina and drove 3 hours each way to see penguins; rented a car in Iceland and drove the Golden Circle; and many times booked excursions/tours directly with locals. Often, I'll research public transportation options at a port, and we'll spend the day on buses, trams, or trains getting to all the sites.