How fortuitous that you bring up Bandol! My husband's cousin and her husband have a second home there. (It was her parents' home.) We will be staying with them for several days in early June. It isn't mentioned here much because it has more French visitors than foreign ones. It has a lovely harbor with many pleasure boats and fishing boats, a nice beach, tons of great seafood restaurants serving that day's catch, and nearby vineyards to visit and taste the wonderful Bandol rose wines. If you are there and have a car, it is possible to do a day trip to St. Beaume or Les Beaux, or Aubagne, Cassis, La Ciotat or Toulouse, or the Calanques, or Marseille. If you like to fish or just cruise on the ocean, many boats are for hire. It is pleasant to walk along the seafront promenade and stop at a cafe for a pastis or glass of chilled rose.
We do plan on visiting a vineyard while there, and have planned an overnight trip to the Drome region to visit the tiny town of Le Pegue to see an excellent but small archeological museum. (We will do more vineyard visits on the way back, as well as seeing some probable lavender fields in bloom.) Bandol is a lovely, relaxing town, and they do have some events at various times throughout the year. Also, one type of souvenir they have there are the santons, Christmas creche characters found in elaborately large creche scenes throughout Provence in December. I treasure the one I got there many years ago.
It is a very pleasant interlude on a trip to France, and with a car you can visit many of the surrounding towns, cities and sights. Have a great trip!