Florence and Tuscany in May with car rental

Two weeks seem like a long time to spend in one fairly small area, but perhaps you've already seen other parts of Italy? In any case, you won't run out of picturesque towns to visit, though they may become pretty repetitive by Day 5 or so (at least they would for me).

I'll tell you how I would develop an itinerary for your time in the countryside. I'd buy a roadmap of the area (should be available on amazon.com). It's common for European maps to mark scenic drives in green, but I don't know that all European publishers do that consistently. I'd want those green lines, though.

Then I'd get myself a guide book that covers Tuscany comprehensively. I'd read the descriptions of all the towns. When I found one that sounded especially interesting, I'd circle its name on the map. When finished, I'd look for clusters of target towns connected at least partly by scenic roads.

Use ViaMichelin.com for travel times, but add some padding.

That's a good point! The postcard hill towns will get old fast.

With 4 nights in the bank, I suppose I can go anywhere, as long as I'm within striking distance of the airport.

There's a Hertz & Avis (used twice) on Borgo Ognissanti very close to SMN train station & easy to get in/out of town & avoid ZTL from there.
Creatiole agritourismo near Pienza highly recommended.

Bologna has a lot of options for side-trips by train (including Ravenna, which is pretty incredible), if you think you might like to go somewhere that wouldn't require driving. Or you could take the train to Rome. You're spoiled for choice in Italy.

With all these solid recommendations, I'm thinking I need to reverse my plan.

1 Airport
2 TBA
3 Countryside
4 Florence

Yes it is always a good idea to spend your last days in the city where you depart from. No car needed while in Florence of course and the taxi to the airport is only a 15-20 min ride from Piazza de' Ciompi.

You should not change agriturismo if you are moving just a few miles down the road. From Castellina to Pienza is not far enough to justify a full move with resettlement in another hotel/farmhouse. Relocating takes time in packing, unpacking and check in/out process.

3 or 4 nights in Florence is good. Not sure I'd spend more than 5 nights visiting Tuscan pretty villages and hill towns. You can of course. There are at least 50 pretty famous ones I could come up off my mind that are within one hour drive from Castellina.

We stayed at il rigo, just outside Pienza - amazing location/views, outstanding hosts, good food and a great "bang for the buck".

I don't think two weeks in Tuscany is too long - you can slow down and take a real vacation if you want. Others are right that you need to do some research, figure out what you want to visit, and then plan your accommodations based on driving times.

Airport- Florence (bus or taxi, bus is cheaper) -train Bologna.

Day trips from Bologna by train

Verona (Peschiera del Garda 15min by train) Ravenna, Parma, or Modena.

Rent car from Bologna. Drive to
Castellina. Stop at San Gimignano and or Volterra on way. Castellina has great access for all of Tuscany.

Drive to Florence. Drop car.
Lots to do in Florence, like the number of days you have planned.

Thanks to all of you! Thanks for taking your time to impart your wisdom and experience. This forum is a hidden gem.

I've been watching anything I can find on PBS, et al, on Italy.

I have one other fanciful dream: to move to Europe on a temporary or perm basis . . . just to break out of this myopic country and try something different. I could marshal between 1/2 a million and a million dollars to pull it off. I've traveled europe for many years and love it but never considered such a move . . . until now.

From one dreamer to another...

When your 90 days are up where to go.

http://foodfuntravel.com/top-5-non-schengen-countries-in-europe-to-visit/

If you are still looking for a place to visit that will be unlike Tuscany or Florence I would consider Lake Como. Perhaps stay in Bellagio or Varenna. and spend a day or two taking the ferry around the lake visiting towns and palaces. It would be a restful way of winding down after a lot of driving.