Hey!

My trip includes:

Flight into Milan MXP - Pick up rental car
4 nights Lake Como (drive to hotel, park car)
2 nights in Tuscany (drive from Como to Tuscany, use car in Tuscany)
7 nights in Positano (drive from Tuscany to Sorrento, drop off car and take public transport to Positano)
3 nights in Rome (take public transport from Positano to Rome)
Flight out of Rome

Does this seem like a reasonable plan? Basically I'd need a rental car for 6 days of my trip, and I'm pricing it out around $337 for a Fiat econobox.

Questions:
* Would it be easier to keep the car in Positano? We are staying in a villa and plan to take day trips. This would add about $350 to the trip (which is fine), but would save some hassle of using busses. (We are very comfortable using public transportation btw)

* Can I easily get from Sorrento to Positano via public transport? Or should I drop off the car in Naples?

* Can I easily get from Positano to Rome via public transport?

In case you are wondering, here's where we are staying:
Lake Como
http://www.grandhoteltremezzo.com/

Tuscany
http://www.follonico.com/gallery_follonico.html

Positano
http://www.villeinitalia.com/photos/IlGozzo.jsp

Rome
http://www.romeoromeo.it/en/suites.html#suite-monica

The other obvious question is

* Should we skip the rental car altogether and rely solely on train/bus/hotel transfer?

I am sure there are diverse opinions on your last question, but based on our experience last week I recommend you skip the rental car. The trains are great. We took the bus in and out of Florence and from La Spezia to Portovenere. All three were very overcrowded, hot and uncomfortable.
Driving other than on the main highways proved to be fairly stressful for DH. He is an experienced and capable driver, but the challenges of foreign signage, heavy traffic, and limited parking were significant.
Enjoy your visit!

It really does matter what time of year you are going, and how many people are in your party.

Also, where are you staying on Lago di Como? Some areas are car-friendly, some are not.

If the villa you have in Positano has parking, that's nice -- however, in many times of the year, once you take your car from your parking spot, using it to go to a popular destination can mean spending a lot of time and money looking for parking and paying for it. (Same can be true of Lago di Como.) If your plan for being in the Amalfi is to use the car to visit other coastal towns, some times of year mean little parking. If you want to keep the car to go to Pompeii, Vesuvius, Paestum, the mozzerella farms, the starting points of hikes in the Sorrentine hills, a car can be an asset rather than a liability.

You will probably want a car in Toscana, but it might be more cost effective and more relaxing if you had a car service pick you up in Malpensa and take you to Lago di Como. Use ferries and buses to sightsee on Lago di Como. Take a ferry to the town of Como to rent your car and head to Toscana. Use the car in Toscana, and use it to get you to Sorrento. But then ditch the car and use public transport and private tour iimos for any other sightseeing you want to do.

There are only two of us, and we are going to be in Italy in mid-June. We're staying in Tremezzo, which is across the lake from Bellagio. I like the idea of using airport transfer from Malpensa and will look into that.

PS - Yes I can keep a car for free in Tremezzo and Toscana. No, the villa does not have parking for my car in Positano, although there is a pay garage close by and I believe free street parking for those agressive and informed enough to find it (outside/above the city).