Just be carefull in Barcelona. It seems that it's the pick-pocket capital of the world. After 2 visits there, both times, someone (and more than one) in our tour group got pick-pocketed.
(And I just wrote all this and realized the ship has sailed…lol posting til I find a useful spot to repost for future Barcelona departures)…. And so is Rome… not sure of the other ports but where there are unfocused, wandering tourists… refresh on ways to prevent being pickpocketed and be aware of distractions and crowds and you have good odds to avoid a problem.
I can also recommennd Hotel Jazz as a lovely hotel near the top of Los Ramblas near the square where you can do a hop on hop off bus. We came from Canada and though I usually suffer from exhausting jet lag the first day when arriving in the morning, we were able to check in to the hotel early and get on the top open deck of a bus for a wonderful orientation around this beautiful city. It’s a terrific port city… very pretty and lots to see. The fresh air kept us going til a regular bedtime with no ill effect!
There’s also a great walking tour company in Barcelona called Runner Bean. I think ours was “free” and runs by tips… truly the best and most charming Irish chap who led us around deserved more than any cruise line prices. You can Google…. Highly recommended. Check for tours like that in your other ports.
Have you tried looking for a group on Facebook for your specific cruise? That can be a good way to find like minded passengers to travel as a private group when you have safe measures of time to go on your own expeditions
Also, I saw a blog on Rome recently where they recommended buying train tickets online rather than at the station to avoid confusion and in his case, his credit card not working on their machine. If you have a travel cell plan, this could be handy to do from the ship when you are sure you are actually going… no illness or weather delay etc.