Stopovers in France - any ideas?

[jobnockey]

Hi there, we're travelling down to the dordogne from calais in August in the campervan and planning a couple of stopovers. I'm just planning and can't decide where to stop!
My ideas so far are Chartres, Loches, Saumur or Langeais... we can do two of these, one on way there, one on way back. We preferably need to have a campsite within walking distance of the town to make life easier and these 4 places do have that option...
any thoughts on any of these to help me make my mind up??? We're happy enough wandering around interesting places but have a 5 yo with us so anything that appeals to him is a definite bonus...
any other suggestions of places I might not have thought of?
ps - the plan is to spend 2 nights in each place so that we can have a whole day in each town exploring.
Thanks!

Saumur is very pretty. There is a castle and lots of little squares and alleyways with cafes and restaurants.

Yes, I'd definitely vote for Saumur as one of your two. Chartres is lovely too. I don't know the other two.

Thank you - I've only just been able to check this thread again! I think we are actually leaning towards chartres on way there and saumur on way back... found a nice campsite too - just have to see if any pitches free.