In reply to oldcheese:
Did you mean this one
https://www.facebook.com/gitemaisse/timeline ? Hadn't thought of this because I have no idea how many people it caters for. Admittedly it's a bit far from the big areas (20-30mn from the Trois pignons or Apremont I think?), and sadly September (the 20th to be precise) is the beginning of hunting season in the Essonne district, so you'd want to stay away from the climbing areas there. On the plus side this gîte is run by Olivier Lebreton, who knows a thing or two about climbing.
If you rent out the whole place you could also consider Gîte Arbonne (
http://www.gitearbonne.com/Accueil-Gite-Arbonne ), which is probably the most central accommodation in the entire forest. Again it's run by climbers.