Oh god, there were too many to count.... although we booked everything on our own and just took the train everywhere at each port.
In Barcelona itself, I highly recommend some of these:
* Montserrat (take the train there and then the arial tram).
* Sagrada Familia
* The cable cars to Castell de Montjuic
In Naples...
* Take the train from Naples to Pompei. You can easily spend a half day there. Make sure to see the old spa / sauna building and all the other interior buildings that you can.
* Pizza in Naples at L' Antica Pizzeria Da Michele for a four euro pizza that is huge. Just bring cash - no credit cards accepted.
In Rome....
* See the vatican. Highly recommend the Vatican Scavi tour. Only 250 people are allowed through each day. Do NOT book this through Disney. They charge HUNDREDS of dollars when they do offer it, and if you request it through the Vatican itself it is just 13 Euros per person! See
http://www.scavi.va/content/scavi/en/ufficio-scavi.html for much more information. On this tour, you will be with no more than 15 people below the Basilica, and afterwards the tour ends inside St. Peter's Basilica and you've bypassed the huge security lines to get in! You actually go through a private security line with the Swiss Guard before entering the Scavi tour.
* For the Colosseum, make sure to do an underground tour and get advance reservations online. Again, this is one to do without Disney on your own.
In Florence....
* Get a ticket WELL IN ADVANCE for the Leaning Tower of Pisa and go all the way to the top.
* We were very impressed with the Cathedral of Florence (Santa Maria del Fiore)
On the Ship...
* Make sure to go to the Snuggly Duckling if it still happens!
SO much more to see in each port ... let me know if you'd like more ideas!