Yes on the toll roads - if you want a nice leisurely drive, set GPS to avoid. If you want to get where you are going in a hurry, use em.
Last year we rented in Avignon and were driving to Carcassonne. Due to a delay, our train arrived almost 3 hrs late, so we were already running behind. We first had the GPS set to avoid tolls and it was going to take something like 3 hrs or so. At about 90 min, we were getting tired of roundabouts every 3 km and I switched the GPS to allow tolls and out remaining travel time was cut in half - from about 90 min to 45 min.
No issues with the roads. We always made sure we had money for the toll roads - we have true chip and pin credit cards here in Canada, but I didn't want to mess with a stubborn cc so we always just used cash.
It is a little hard to watch your speed when you are trying to drive the speed limit and locals are driving on your tail - I guess they know where the speed cameras are...sigh. If you are driving a mid-size or bigger car, I'd opt for outdoor parking areas if possible. We had a Citroen Cactus and some of the indoor parking was really narrow spots (this is more of a midsize - about the size of a Ford Fusion - smaller than our SUV which is an Escape) and we ended up getting a huge scratch on the car trying to navigate a tight corner in a parking garage. So we are going to avoid indoor garages from now on when we rent.
As for things to see - we've seen Pont du Gard on two occasions and really enjoyed it. And Rousillon was gorgeous if you like snapping photos! We enjoyed Les Baux as well last year if you are into ruins.