We will be driving from Lucca to Rome on a Saturday in August. Is it feasible to stop in Bagnoregio for a quick look around and lunch on our way to Rome??
Sure, why not? All roads lead to Rome and away from Rome. Not sure what you are asking.
With a car it is easily accessible. It's real small, you can do a quick hour stop or spend 3 hours there and have lunch.
Just remember that you can't drive into Civita. You have to park outside and walk up the hill.