This is our first trip to Italy. We’re starting in Rome and working our way north via Florence, Siena, Cinque Terre, and ending in Venice. We have two weeks. We want to use public transportation except when we’re in Siena. Does it make sense to go to Florence first, then go to Siena and rent the car there (and return it there), or go straight to Siena, rent the car, then bus/train to Florence? Thanks for your help!
You will have better rental options in Florence
I would go to Florence from Rome
Pick up car as you leave Florence, keep for Siena then drive to CT and drop the car at LaSpezia
Make sure you have easy parking at your Siena lodging
All drivers must have an IDP-required by law
Do your homework on driving in Italy-ZTLs, parking, speed cameras
We always book our cars thru AutoEurope.com
It is easier to get to Florence from Rome (direct fast train) than Siena from Rome (bus from Rome or train to Florence then bus or train to Siena)
I think the Rome-Florence fast rail connections probably make that a better 2nd destination.
Renting in Siena probably ends up saving you money because you don't need your car the first day or two. Plus you avoid the hassle of driving in Florence. FWIW, I didn't really mind driving in Florence but everyone has a different comfort level.
Choose a smaller car if you can. Something like a BMW X5 is a relatively massive car in Italy. Lanes and parking are very tight so save yourself those headaches by downsizing from what you're used to in the states.
Month and year?
You have good advice from Christine. Note that Siena is the opposite of "flat", so consider hills you might have to climb if your parking is far from the hotel. Regular navigation Apps do not embody the ZTL's, so they will tell you to drive straight through the center of Siena, if you are not paying attention.
You don't say that you will be driving to see smaller Tuscan towns while in Siena. You certainly don't need a car to see (large) Siena. Be sure to book the major sights in advance, including the Cathedral.
I personally have trouble getting an automatic transmission actually delivered on pickup day in Europe, but there aren't a lot of similar complaints posted here.