The port is a long way from the city, so be prepared to pay to get between the ship and Barcelona. The taxi drivers overcharge, so get a price before you get in the car. There is lots to do in Barcelona, so plan your time well.
Again, the port is a long way from the city, so be prepared to pay to get between the ship and city. The city is dirty, and it was difficult to find much to enjoy. Seek out the local crepe diner for a treat, and enjoy a cold beer, which you can drink on the street.
Florence is an hour from the port, so be prepared to travel. We did an excursion from Cruising Excursions, and it was excellent, and much less expensive than the Carnival excursions. There is a lot to see in Florence and Pisa, and it was very crowded. Be prepared for lots of walking.
Rome is busy and crowded, and plan to loose 2 hours for travel to and from the port. We did an excursion from Cruising Excursions, and it was excellent, and much less expensive than the Carnival excursions. There are also plenty of taxis willing to take you to Rome for the day, and that may be a better deal for large families and groups. Plan ahead if you want to see the Vatican Museum or enter the Colosseum, as the lines are very long.
Venice is not the city of your dreams! Be prepared for a long walk to the water taxi, and be ready to overpay for everything. The city is overcrowded with tourists, and the vendors take advantage by overcharging. It is difficult to find your way in this city, and nearly impossible to get back to a shop that you passed earlier. The water taxis are overcrowded to the point of being unsafe.
My best advice is to stay away from the main areas to find the best deals and space to enjoy yourself.
This city is a pleasant surprise, and walking the fortress wall provides a great view of the old city. It does take a long time to walk, so plan accordingly. There are many fine little eating places, and most of them seem local. The old city is a long way from the sea port, so be prepared to pay for transportation.