How many days maximum to spend in Florence

Not at all!! Florence really requires 3-4 days to experience most of the sights without being in a hurry and savor the city. End of November will be great, as visitors start diminishing and you can enjoy it without too many crowds.

I would use the other days to take the train to Pisa and Lucca on one day, and the bus to Siena on another. Both give you a good sense of the rest of the region. The last day you can arrange to join a group tour (you decide whether small or large) into the Chianti wine area for some organized visits to wineries and wine tastings. Take a look at some here:
http://tours.discovertuscany.com/en/8357/Tuscany-tours/Wine-Tasting-and-Winery-Tours/d206-g6-c21
 
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