Barb and I took a Med cruise last October. We flew into Barcelona a day early to see the sights. Glad we did. Barcelona is a beautiful city. In twelve days we went from Barcelona to Cannes, Cinque Terre, Rome, Kotor, Venice, Dubrovnik and back to Barcelona. We loved the whole cruise. The only thing that was a bummer was in Rome. I didn't get into St Peters. That's something I wanted to do since I was a little kid. Our tour into the city was on a Wednesday. It was a perfect storm against us. Turns out the Pope gives blessing to the crowd that day and the place was packed. It took forever getting into town on the bus. I think it was our tour guides first day on the job and by the time we got to St Peter's square (Which is round) we didn't have time to wait in the humongous line. I just had to recall what it looked like from pictures.....not the same. If that's something you want to do you might check on tours that can get you in for sure. Venice is what I liked the best. I was there 40 years ago in the Navy. see the photo below of a shot of mine from 1969 and one from last fall. Still my favorite place.
Another thing, if you go to the casino in Venice guys need a dress jacket. Women had no real dress code, so Barb was able to go upstairs and get some chips for me.