When in Livorno, we hired a taxi for the day. Not a tour guide, just a taxi/cab. It was waiting for us when the ship docked and took us first to Pisa for a short stop. It was early am and very few people there. Kids loved it.
The taxi then took us to Florence and just dropped us off. We had made reservations to see "David", so we walked right in without a wait. Again, kids thought that was really "cool". We then just wandered around Florence, very walkable, stopping at some sites we had already decided on pre-cruise. We had lunch, ice cream and our taxi was waiting for us at the meet up stop. We arrived back at the ship with time to spare. It was one of the favorite stops for us and and the kids. Very relaxed and Florence is beautiful.
So do some research, and depinding on what you want to experice, don't eliminate the stop due to the distance.