Michael, Since you do not mention your itinerary I will try to give you some very general information. We have been on over a dozen Med cruises, and have only used a ship tour on two occasions. So the quick answer is no, you do not have to use their tours and yes, you can do things on your own. However, the fact that you are asking this question a week before your cruise makes me think that you should probably give strong consideration to simply using the cruise line tours. Independent travel (anywhere including the US) requires doing some pre-trip homework in order to maximize your enjoyment and mimimize your hassles. If you still want to do some "homework" I suggest you spent some time at a large local book store (like Borders) reading travel guides to your ports, do some research on the internet, make some decisions as to what you want to do in each port, and than consider whether you can best achieve your goals by taking a tour (they do get expensive) or going off on your own. Since you say you are going to be in Venice, I would suggest that this is a good starting point which just happens to be a place that can easily be done on your own with just a little reading.