I would suggest you look seriously at Assisi. I am there as part of an international music festival for about 3 weeks every year. INHO Assisi has more to offer than Orvieto (which I like as a day trip and we send our performers there every year for a break). Assisi will be primarily religious art focused. The 3 levels of the Basilica San Francesco are breathtaking. You also have a half dozen or more churches that are older including Santa Maria Maggiore, which was the cathedral until the 12th century. Beneath it are Roman ruins, beneath those are Etruscan ruins. 2700 years of history! The RS book has a lot of detail for you. Also, check out YouTube videos and the webcams. These will give you more an idea of the medieval beauty the people have maintained or restored after the 1997 earthquake. Food? Not sure you could go wrong there. Umbrian recipes are especially delicious. La Lanterna ,on the road up to the current cathedral (since the 12th century) San Rufino, is a personal favorite. Hotels? Try Hotel Sole (a wonderful bnb run by my good friend Michaela). It's on Via Santa Chiara (also known as Via Mazzini) in between the church Santa Chiara and the Piazza del Comune. Across the road and closer to the Piazza is Hotel dei Priori. On a lower level (Assisi is built on the side of a mountain) is the Hotel Giotto. We put visiting groups of performers there and they have always had good thing to say. Magnificent view! Right across the road is a small shop where you can get the most amazing olive oil and balsamic vinegar. Francesco Mollaioli is a delight! Assisi is a wonderful place both day and night. The views of the valley and the views up the side of the mountain are powerful. There are local artists who have captured the beauty and spirit of Assisi. Cruciani and Martini are my favorites. Leather goods also make for good shopping. Make sure you try the wild boar - great sandwich!
edit: oh yes, skip the car! you won't need it in Assisi and you'd have to park it quite a distance away.