tedgale:
Your post was timely. We're considering dropping San G. if we can't be there in the evening. We'll leave the day trip consideration until we get there. If anything, we would probably now choose one to the Chianti region.

I think we'll do as suggested above: spend last 2 or 3 nights outside Florence (including the last in Bologna). Haven't decided whether to head to Tuscany for a couple of nights or spend those last days around Bologna. I'd say we're still leaning toward Tuscany, but Bologna/Ravenna sure would be easy.