No problem, I'm glad to offer suggestions and help point you in where to look
.
As far as car rentals, not sure what you have found so far but I know ever since the pandemic hit, car rentals companies sold off their fleets and now their trying to catch up because cars in general cannot be so easily found (pandemic + war makes it hard for some pieces to be found).
I would suggest doing searches through a specialized search engine such as rentalcars.com - you can do a search here (it is our affiliate link, so if you do book through here we can a small commission, no extra cost to your rental):
https://www.discovertuscany.com/tuscany-car-rental/car-hire-in-tuscany.html
As far as what to see in the area, you will be able to see/do lots! I wouldn't make a fixed schedule but a plan of places and then set out each day and see how it goes. With a small baby, you'll have to see how long you can be in a car and out and about. The baby might actually sleep a lot being out and about, it will be you who will be tired!
Here are some ideas - I think you'll need to decide what to skip!
- a day in Chianti, spent among the hilltop villages such as Gaiole, Radda, Castellina (that's the closest to Romitorio, with restaurants), Panzano and Greve
- a day in San Gimignano and exploring smaller towns nearby, such as Certaldo, San Donato in Poggio
- a day in Siena (stop at the Monteriggioni castle on the way back)
- a day in Volterra, with a stop at Colle Val d'Elsa on the way there or back
- a day in Arezzo - it is a delightful town, usually off the radar.... but if you want a day at the beach, maybe this is the one you can skip
- a day spent in Montepulciano and Cortona
- another day spent between Buonconvento, Montalcino, San Quirico d'Orcia and Pienza. You can actually spend two days in the area, going more slowly and add in a stop at Bagno Vignoni, there are outdoor hot springs (make sure to read this page:
https://www.discovertuscany.com/valdorcia/bagno-vignoni.html
- a day in Pisa and Lucca - or another day at the beach
- a day in Florence, of course! This could easily require two days, actually. You decide. Here are some options for a day:
https://www.visitflorence.com/itineraries-in-florence/florence-in-24-hours.html and in 2 days:
https://www.visitflorence.com/itineraries-in-florence/two-days-in-florence.html