Because I was driving to Cinque Terre and the Amalfi Coast, and car parking was either non-existent or the cost of it through the roof, we stayed in places outside the main areas - where as a bonus the hotels were more luxurious and cheaper.
We stayed ar Deiva Marina (Hotel Kriss) just outside Cinque Terre, and it was a short ten minute train trip to the first of the Cinque Terre towns - where one has to buy another train ticket to go between the towns. If you get bored there (you can see the five main towns in a day and a half), a day trip by train to La Spezia is good, although one needs a car or boat to go to Portofino or Porto Venere easily. We grew very fond of Deiva Marina.
At Amalfi Coast we stayed at Maiori (Hotel Panorama). You have to catch the bus into Amalfi, Positano, Sorrento from there, or the boat to Capri. But it doesn't matter where you stay there - you'll have to catch the bus to visit the other towns (unless you are crazy enough to drive). Maiori is the furtherest point from Sorrento, but closest to Salerno - where you can get a train for a day trip to Naples. We really missed Maiori when we left.
Venice - we stayed near the train station, which is a fairly lively place at night.
I have to concur with the earlier comment. Two days in Florence is not enough - especially if you don't pre-book tickets to the Uffici Gallery and the one with David - you'll be waiting two hours in a queue at each to buy tickets. I also especially liked the science museum which had Gallileo's telescopes and his hand with his finger sticking up.
Regards,
Renato