Borro is owned by Ferruccio, and Borgo is owned by Massimo, I think... Borro is lovely, particularly if you can stay in the main villa. And the other villas and farmhouses are great for families or small groups of friends. They've made huge investments in the estate, winery, agriculture, village, spa, etc. which are now paying off, and I think it's fantastic. (I haven't been to Borgo, though, so I don't know how they compare.)

In Florence, how about the Lungarno as another option? It's not the FS, and I haven't stayed there, but it's got a great location on the bank of the river and an excellent restaurant (Borgo San Jacopo) which is worth a trip. Saw the other day it was available in a Jetsetter.com sale. I agree with vuittonsofstyle re the Grand Hotel Villa Medici - we tried it out a few years ago and got upgraded to a nice suite, but the place is faded, the location a bit inconvenient, and service was slightly Fawlty Towers.