Which day would be better for a day trip from Rome taking into consideration shops, restaurants and sights on a Sunday vs. Saturday.

Saturday - by far. Many of the non-touristy shops will be closed on Sunday.

Stu Dudley

I'll agree with Stu. You will want to spend time in the beautiful Duomo, and on Sunday there will be several masses. You could certainly go to mass at the Duomo, which I expect would be a memorable experience, but you couldn't wander around the interior, which is worthwhile. Orvieto is beautiful, and there will be a lot to do in town (underground tour, Etruscan museum, St. Patrick's well) on a Saturday. If you extend your visit, the Hotel Duomo (just about a stone's throw from the Duomo) is a great option: inexpensive and friendly. Be sure to check out the gelateria (it faces the back left wall of the Duomo) on the main square. Enjoy your visit!

>>Be sure to check out the gelateria (it faces the back left wall of the Duomo) on the main square<,

I'll second that !!!

Stu Dudley

A fresh news about Orvieto.
Maybe you know the restaurant L'ASINO D'ORO; IMO one of the best (let's say the best) in the center of Orvieto.
On next spring they will close in Orvieto and they will move to Rome (Montesacro).
A sad news for Orvieto, a good news for Rome.

Vincenzo

If you have a chance to stop in Orvieto go to visit Pasticceria Adriano and meet the chefs Sergio Maria Teutonico and Maurizio di Mario. They have a huge underground cellar where you can have dinner or lunch on reservation.
www.dolceorvieto.com