Renting a Car

It depends on how much time you have and where you wanted to stop. Are you talking in a day or over several days? It is not advised to leave your car parked with anything in it--even the trunk. I've taken this risk, full disclosure, but I have also read numerous stories of people having their clothing stolen.
Car travel is great for rural areas and small villages, but for getting from place to place, the train is best.

Read this about driving in Italy and restrictions involved [ZTLs]; do not leave anything of value in a car when parked:

http://driventoit.blogspot.com/

Because of the ZTL issues, while the preferred means of traveling around the countryside, driving is not an efficient means of travel between cities; not recommended at all down around Sorrento and the Amalfi Coast.

Ok, thanks. Maybe I will rethink renting the car. I was just hoping to have time to take a few quick stops along the way. What would you recommend as the best way to see the Amalfi Coast in 2 days?

If you only have two days on the Amalfi coast, then you don't have time to meander down there! Take the fastest train to Salerno and then a ferry to whichever village you choose. I'd go to Positano and not leave town unless hiking or going on a boat trip.

Sorrento is not on Amalfi coast
You do not want or need a car anywhere in Sorrento or Amalfi

Above suggestion of train to Salerno then ferry/bus to Amalfi or Positano is your best bet

After these 2 days where are you headed?

Yes, we rented a car on our way out of Florence, stayed in guesthouses outside Siena and Orvieto, turned the car in to Orvieto six days later and took the train(s) to Sorrento. Wouldn't recommend driving this route in much less time.

You're talking a 320+ mile trip, 4 1/2-5 hours if you drive. The train will get you there in much less time.

Florence to Sorrento? Take the train. We rented a car in Florence for a loop in Tuscany and returned the car and took the train. Driving in Italy’s is pretty wild, but driving in Naples is downright insane. Just don’t do it. Florence to Naples is a great train trip at 250kph. Transfer to the Circumvisuvia line right into Sorrento. From there it’s a half hour ferry ride to Capri, don’t miss that.

When is your trip? In high season, the Amalfi Coast is crowded, expect lines to board buses and ferries. Buses are slow (the road is narrow and lots of traffic, virtually no place to pass). How many nights there? 2 days to see the AC means a 3-night stay. For such a short visit, Salerno is a better choice, since there are fast trains from Florence (and back north to . . . wherever). To get to Sorrento, you need to transfer in Naples from the rail system to the local Circumvesuviana, really a metro that only runs twice an hour and is often crowded.