Civitavecchia is the stop for Rome...people go in by train but it can be risky time wise, a couple of hours by road but we did the ship-trip.
Barcelona is an interesting place to just walk around, our ship had a free bus to the base of Las Ramblas (main street)
Lisbon...watch out for the big bridge when you sail in, depends where the ship docks what you can do on your own, there are interesting trips but again an interesting place to walk around, some really nice restaurants in the Marina by the bridge. Haven't been to the others.