Itinerary help

Three nights in a location gives you two full days when you consider travel time. It seems fine to me except for the two nights in Florence. I would add more time there if you can.

As for driving in Florence, be sure to get exact, specific instructions from the rental company on how to reach their shop so you can avoid crossing into any ZTL's.

Donna

You might consdier droppping the car at the airport. That is less hassle.

Don't now your preferences but you have a lot of time in 5 Terre and Cortona. I agree with the above, an extra day in Florence would be nice.

We have dropped off a car at the Florence airport. And the next year we rented a car in downtown Florence, so we've had experience with both.
The downtown location, which was just outside the ZTL, was walking distance from our hotel, so we walked over, picked up the car, drove to the hotel to get our luggage (which was also outside the ZTL) and then drove out of Florence. Not a problem at all. Just be careful with the ZTL's - we've been caught in Bologna, and we thought we were being so careful.
When we returned the car to the Florence airport, we were looking for a big sign for the entrance to the airport, and there wasn't any. Coming from the US, I think we expect signage to be bigger for a 'big' city airport, but the sign was extremely small, we missed it, and drove a few miles out of our way to find our way back. If we hadn't missed the sign for the airport, returning there would have been easy, but we did miss the small sign. Be aware.
We loved Cortona. But, I totally agree that you need more time in Florence. Personally, I think 2 nights in Cortona is enough, unless you're using it as a basis for touring Tuscany, I'd rather spend more time in Florence. A must in Florence, since you have a car - go to Piazza Michaelangelo for the views. It's wonderful both during the day and at night. And, since you'll have a car, just southwest of Florence is an American Cemetery. We had been to Normandy earlier, and this was a smaller version, but equally impressive. Someone had recommended to us to go and we weren't disappointed.

Thanks for all your responses. Did anyone pick up a car in another city and drop off in Florence. Any hotel suggestions in Florence that is close to train station.

You could pick up your car in La Spezia. Are you staying inside Siena? Or outside? Consider where you can and cannot drive.