I'm planning a 4 day trip to Umbria. I'm taking a train from Rome and staying in Perugia. I was going to rent a car from there to see all the other towns. Is that wise, or should I just take trains everywhere, since parking seems to be so difficult?

It all depends when you're going as to whether parking will be a hassle. I personally enjoy the freedom of having a car to be able to go at any time you want. We were in Perugia, Spello, Assisi, Spoleto and Deruta at the beginning of March and I don't think we could have done it without a car.

We spend a week in Tuscany, and I liked having a car and not being held hostage by bus and train schedules -- I liked to get up and go when I wanted. To me it was worth the expense of having a car.

It depends to some extent on the towns you want to see. Assisi, Spello and Spoleto are all on the same train line, but be aware that in each case the train station is down below the town and you have to take a bus (Assisi), a taxi (if you can get one, or walk: Spello); I don't remember whether there was a bus in Spoleto; I was staying several days so took a taxi with my luggage. As far as I know, there is no train between Perugia and Deruta.

Renting a car would undoubtedly give you more time and freedom.

Thanks everyone, I really appreciate all the advice!