Visiting in September and looking for the best places to explore.
There are so many! We live in Castel Rigone, a beautiful small medieval hilltop town . There is an excellent hotel, Relais la Fattoria. Very good location for visiting nearby Assisi (a must!) Citta delle Pieve, Perugia (magnificent) Panicale, Cortona , Montepulciano(beautiful and so is the wine!) and yes, further away, about an hour, Orvieto is incredible. My blog will give u some idea of the area.
AngloINFO Umbria is also extremely useful.
http://umbria.angloinfo.com/ over 5 years ago