In reply to TomGB:
Crusty VS cliche? Well you could have a lot of fun getting some easier circuits done instead of sessioning harder problems.
Chateaus - lots. See what's near your campsite/gite. Might have odd opening hours though if it's a small one.
Fontainbleau market is good, as are some of the other smaller markets.
Train to Paris for the day.
Cheese? - Local cheese shops in the Barbizon area. Impressionism too, -The Barbizon School Museum.
I reckon a combo of circuits + cheese and art would be pretty good.