Rental car in Tuscany

Your call on that.
If you are ok with a 6 hour drive and probably paying more if there are 2 of you considering gas and tolls compared to the train tickets than drive.
The train is high speed Florence to Naples so would be faster than driving but backtracking to Florence to return a car and then board a train ; which you then have to change in Naples to reach Sorrento will likely eat up similar time as the long drive.
Overall timing is probably close to a wash.

Either way you will have to research driving in Italy before you travel (need an IDP, research ZTL zones where you may drive, the speed cameras, the tutor highway speed system, signage like ZTL and bus lanes, etc...)
Can be easy driving but if you don't research before hand can be a very costly vacation.

If driving I would not go to Naples at all, if there is a rental office in Sorrento that would be my choice of drop off spot.
Just FYI: Naples is a place I would never drive a car, to the airport only.

I would also not rent from Budget rental in Italy. For Italy stick with the big 3: Europcar, Hertz or Avis. All 3 are good so whichever is cheaper. Stay away from the others including Budget.

Drive and drop the car in Sorrento.
By the time you backtrack to Florence and take trains (change in maybe Rome and Naples, then switch to the Circumvesuvian in Naples it's faster.
By using the car you only move your luggage once.

Time about 5 1/2 hours without stops for food (Autogrill is good) or fuel.
Tolls are about€30 and gas €40.

If you decide on the train, try to take the one that doesn't stop in Roma Termini.

I will stick to the original plan and train down to Sorrento. Do you have any links where I can research to better prepare myself for driving in Tuscany? As for the Budget rental I will look into changing to one of the three you mentioned below. If I am stuck with Budget, is there anything I should look out for? THANKS!

Thanks Gerri. Will research both options

Here's a good explanation on driving in Italy. Download their free PDF.

https://www.italybeyondtheobvious.com/dont-mess-with-ztl-zones

thanks again! Any recommendations for a website to book my rental car?

Jason, if you decide to only use the car from Florence to a farmhouse outside of Siena and day trips in the general Tuscany area there is not much to fear or need to research.

You will need an Internal Drivers Permit to drive in Italy. In the US, that is simple just have to go to a AAA office and pay them about $20 for one, takes about 20 minutes. In Canada I am sure there is a similar process.

This link is good for what signs look like.
http://italyexplained.com/driving-road-signs-italy/
The ZTL one is the most important one you want to know about.

If in Florence prior and not the airport I would rent from the Via Borgo Ognissanti office (both Hertz and Europcar have offices on that same street meters from each other)
It is near downtown Florence and the train station where the airport is far from town, unless flying in and renting of course.
From there you are inside a ZTL but it is a straight shot out to the main artery around town which leads to the highway.
They will give you instructions on how to get out and onto the highway south towards Siena.

In Siena and the other small towns: just don't drive through any ancient walls gates ; they will be fairly obvious in these smaller cities and the all towns ZTL's will only be inside the ancient walls where the historic centers are.
You have to drive and park on the outskirts of those and there will not be any ZTL fears then, know what the sign looks like.

As far as bus lanes, Florence would be the only place to watch out for them
The tutor system monitors you speed on the highways ; you will see signs that say Tutor to let you know you are in one of those monitoring zones ; they are only on the highways and for your travel you may not see any.
In any case just keep you speed near the speed limit and you will be fine.

Speed trap cameras are everywhere in the region. Al over the highways and typically on backroads as you approach a town.
There is a warning sign of one upcoming and if you use a map app like WAZE on your phone for navigation it will give you advance warning and advise the speed to be under ; which is fantastic.
Without that you would need to pay attention to the speed limit signs.

That is about it otherwise, nothing to be concerned with. Traffic is not really an issue other than right around Florence.

Budget is fine in the US or Canada but operated completely separately in Italy and they have a bad reputation for service and bad practices. That could mean a junky car, hard upsell on insurances, fake claims of damages after if you don't buy their insurance. All of things you could imagine if a rental agency was not reputable. It seems all companies operating in Italy other than the big 3 I mentioned and I think Sixt is also fine have really bad reputations.
For a good rate including Insurances at the big 3 options to give you peace of mind have a look at
www.autoeurope.com
They are a consolidator but many times cheaper than booking direct and almost always cheaper if paying extra for the full coverage insurance ; very reputable and actually based out of Maine not Europe.

Check Kemwel, sister site to Auto Europe. Prices are sometimes less even though owned by the same company.

https://www.kemwel.com

Drive! We picked car up at Rome FCO, toured Umbria and Guscany for two weeks, then drove to Naples where we dropped car off. It was cheaper to drop it off in Naples than returning it to FCO. The drive was easy, all autostradas, like US interstate highways. We dropped car off at Naples airport and took a taxi to our Naples hotel. Since you’re staying in Sorrento, drop it off there.

A bit puzzled by the advice to drop Budget in favor of Avis, et. al..

Avis and Budget are the same company, i.e., Avis Budget Group. ( stock ticker 'CARS')

AutoEurope/Kemwel will often put you into a Hertz car. Then turn it in at the Orvieto train station Hertz office and take the 70 minute train ride into Rome Termini. You can catch fast trains there down to Naples and the Sorrento area.
I try to pickup car rentals in city locations to avoid extra taxes and/or rolls vs. airports. Hertz has a city location in Sansovino 2 miles by taxi from the Florence train station.

Book through AutoEurope or Kemwel (sister companies). They are consolidators and you can choose from Hertz, Auto Europe, Avis etc. Get their no deductible insurance rate for collision and theft. Buying the no deductible rate from Hertz, Avis, etc.is extremely expensive.

It's Italy, you want the zero deductible collision.

Tank you all for this great info. Auto Europe is a awesome website, great customer service. Booked Avis rental downtown location. I think we will be returning the car back to Florence and train through Naples, being that I have already purchased the train tickets.

On a side note. My wife and I were hoping to stop in Naples for some pizza before heading to Soprrento. We will have our luggage on us, is it safe to pull this off, or can we store our luggage at the Naples train station, OR will this be a waste of time just for the Naples pizza experience.

Thanks again, This forum is amazing!!

Leave the luggage at the baggage storage (Deposito Bagagli) at the Napoli Centrale station. The service is outsourced to a company called Kipoint..
Why carry extra weight? You won’t go bankrupt, the storage fees aren’t exorbitant. Just €6 a piece for the first 5 hours.
http://www.napolicentrale.it/en/service/detail/left-luggage

There IS luggage storage at Napoli Centrale, but it charges by the piece (unlike renting a big locker which can hold several smaller bags) so you could be adding $20 to the cost of that pizza. Was worth it to us to visit National Archeological Museum for a few hours.

To Joe's question ; my understanding and I could be incorrect is in Italy all of the brands have merely licensed their name to be used. They are not franchise locations backed by the national HQ like a US or Canadian office might be.
Hence you deal with the Italian divisions only ; Avis HQ will not get involved should you have an issue.
Therefore, I am not sure if Avis and Budget are the same ownership in Italy or completely different companies.

Have heard many bad stories about Budget and usually more good than bad about Avis.
On Auto Europe's website they show a 3 star rating for Budget and a 4.5 star for Avis, Hertz and Europcar.

Another reason why I like Auto Europe another person in the mix to go to bat for you should any issues arise.

For Italy mainly because of the whole ZTL and speed camera issues that hit unsuspecting travelers months later ; there first complaint is usually to the rental car company instead of blaming themselves for not researching in advance ; so all rental car companies in Italy have more negative ratings than they likely deserve.

Budget rent a car in Florence is inside the same office as Avis rent a car, on Borgo Ognissanti 128/r, as the two companies have merged some years ago.
So if one rents from Avis to avoid talking to Budget personnel you are not going to be happy with the results.