Monterosso to Florence Airport

Trains need a station and the Florence airport doesn't have one. There's a new tram from Santa Maria Novella station, T2 about every 6 minutes. If you haven't bought airline tickets yet, consider flying out of Pisa. https://www.visitflorence.com/blog/tram-line-t2-open/

Have you checked for rental car pickups elsewhere? I would not go all the way to Florence airport from Monterosso to get a rental car. People often get them at La Spezia.

and then shuttle or taxi to the airport to get our rental car.

There is a tramway stop at Florence airport. It's always rails but not the type used by Trenitalia's trains.

I'd pick the car in Borgo Ognissanti road, if you prefer the airport You can get on the tram from outside Florence SMN station. I have no idea how far the airport tramway stop is from car hire companies.

Thanks for all your help... I've read in many places that it is a nightmare getting out of Florence central by car and that's why we are getting the car at the airport and then heading south to our Tuscany getaway. Sounds like the tram is a good idea.
Thanks!
Tim

Yes, but from Monterosso you are just 25 minutes by train from La Spezia, where you could get the car and not spend a few hours+ in transit to do so. It may require more driving depending on where you are going, but it's not difficult driving. You could also do Pisa airport, also not a difficult place to pick up. Just want to make sure you compared all of your options!

Why not get the rental car at Pisa Airport where many rental companies operate? Train to Pisa Centrale and then the train shuttle called the Pisamover to the airport. (You can also rent in La Spezia though options on Saturday may be limited.) Driving from Pisa airport is easy-peasy as it's on the edge of town where an expressway called the SGC Fi-Pi-Li begins. You'll be closer or equivalent in distance to Volterra, San Miniato, Certaldo Alta, and San Gimignano compared to Firenze.

Thanks to everyone in this amazing group!
The plan B using Pisa is really looking good, they even have the high speed train to Rome, so no need to go to Florence!
We will however do a day trip there by regional train while we are in Tuscany.

Be aware that only the Pisa-Rome Freccia trains routed via Florence use the high speed tracks.

The plan B using Pisa is really looking good, they even have the high
speed train to Rome, so no need to go to Florence!

You don't have to drop the car in Pisa if that is where you pick it up. We've never been charged a drop off fee in Italy.
Where are you staying in Tuscany?