La Clos de la Violette in Aix was the only really fine dining experience we had on a trip in '98 where we saw kids at dinner-- they seemed to handle it fine, but other places we ate (ie Ducasse) the kids would have been pretty unwelcome, I think. Perhaps relatedly, it was the least impressive of the three really fancy places we ate, but it was a nice meal and a nice atmosphere.
In Avignon we ate at some place that was in Patricia Wells' book (don't have it handy and anyway, the book was several years un-updated at the time) but I frankly wish we had tried our luck. It was all right but a bit dowdy, while there seemed to be lots of new places around it which were very promising-looking. All in all, I thought Avignon looked well worth exploring to find which of the new places was best.
Beyond food, I highly recommend going to Nice, especially a bit off season; we liked hanging out on the beach in sweaters in reading, and gathering lunch in the market (the Cour Saleya), a lot. I would have spent the whole two weeks there, frankly. St. Paul de Vence was a nice (no pun intended) day trip and I bought some excellent regional wine at a shop there, I especially liked one he recommended called Berthe-Mas or Mas-Berthe, I think. There's a contemporary art museum around there with a lot of outdoor sculpture we liked a lot.