Palazzo Belefiore looks promising. http://www.residencebelfiore.it/
Looks like we would need to rent two apartments for about $3000 total for the week.
Clarissa, with its frescoes looks particularly interesting. Pictures also at:
http://www.papaverorentals.com/property_detail.cfm?PropID=20030922170654&PropReferenceNo=F23-25#cal
Orsanmichele looks like it might be perfect. I haven't yet checked price, but it looks
like it is available the week we want.
http://www.italyrentals.com/catalog/ViewProperty.aspx?id=3870&s=2007/06/23&e=2007/06/30
The frescoed ceilings in this one look very nice...$3380 for the week. Don't know if it's available.
http://www.traveltuscany.net/property_detail.php?idunit=2822
What looks to be the same one is listed at $3076 here (but maybe that's low season)
http://www.apartments-florence-italy.com/apartments/apartment.php?ID=A275&valute=USD
This one is fun just to look at (not available):
http://www.papaverorentals.com/property_detail.cfm?PropID=20051025135900&PropReferenceNo=F15
There are a bunch together in this building:
http://www.papaverorentals.com/property_apartment.cfm?PropID=20050303142545&PropReferenceNo=F41
This one is sort of cool as well, sort of strangely furnished, though...no prices given:
http://www.florencevillas.com/property_detail.php?idunit=2039
If we wanted to go truly high end, there is a villa available for $9750 (holds 10 people).
http://www.luxury-villas-in-tuscany.com/f207/index.htm