In reply to EricH: Just got back from the Tarn, we stayed at Beldoire in les Vignes. Very nice place, river, pool, decent facilities, 30 min walk to crags. I'd recommend it.
In reply to EricH:
Sweet campsite, right next to the river, just down from Pont d'Arc. Nice people, also does kayak and canoe rental. Really recommend it
For the Tarn - Les Peupliers @ Les Roz is ok and you can walk into town.
For the Ardeche the one at Mazet Beach is great. If you are lucky you will get a spot next to the river. Quiet and with great climbing on the doorstep.