Starting to make reservations. My dd thinks I need to see Assisi. Sounds good to me. Going to take the recommendations from this site and stay in Siena several nights and take day trips around the area. Still trying to decide about Venice. I have 7 days.
Liz, Assisi is our favorite hilltown. Even now, I have my wife and her daughter booked there for a mother/daughter trip. From Rome to Assisi, it's a 2.0-2.5hr train ride. Then, the Assisi train station is not in Assisi - it's down the hill. You then need to take a taxi or bus up to your hotel. It is a great visit. Next, the trip from Assisi to Siena is really a hassle. By train, it's a 3.0hr-5.0hr trip with 2-3 train changes. You either go through Florence or Chiusi. There is a bus but it only runs once a day. My wife will have a rental car for her visit to Assisi and Tuscany. As for your visit to Venice, I would suggest that that is a very tough fit into your schedule. Worse yet if you have to return to Rome for your flight home. If you were flying into Rome and out of Venice, you might be able to squeeze in your last afternoon and evening before your flight home. Still, it will be a squeeze.
If you want you can rent a car from the Perugia airport, which is close to Assisi. The best public transport solution, otherwise, is to go to nearby Perugia, Umbria's capital (several buses, trains or taxi from Assisi) There is a bus that leaves from Perugia train station every morning for Siena. Currently it departs at 10:40 am from Perugia. Travel time to Siena is 70 min. There are no buses from Assisi to Siena, at least none I could find.
Go to www.baltour.com
The bus from Assisi actually leaves from S. Maria degli Angeli, the same town that has the train station. The bus leaves at 10:20, it is the same bus that leaves Perugia at 10:40.
Ditto Henry. The Assisi train station and the bus stop are both in S. Maria degli Angeli which is just down the hill from Assisi. The bus stop shown on the www.eurolines.com website (Eurolines, Balfour, Sena), is not at the train station. It's a plaza a short distance from the train station. I'm not sure if the bus stops at the train station on the way to Perugia. Also, there are 3 buses that serve Assisi - Line A, Line B, Line C. I know that Line C stops at the train station as we have taken it there. I'm not sure if it continues over to the Eurolines bus stop. I bet the nice lady in the tabacchi shop at the train station knows the answer. I know she sells the bus ticket up the hill to Assisi. Perhaps she sell tickets on the bus to Siena as well.