Close to IPN:
. Hotel d'Orsay
2 rue François Leroux
RER B station : le Guichet (from Paris, one station before Orsay-Ville)
5 minutes by walk from the station
15 minutes by walk from the IPN Orsay (map)
. Hotel Le Village
4 rue Neuve
RER B station : Gif-sur Yvette (from Paris, 3 stations after Orsay-Ville)
You can choose hotels nearby a connection with RER B network. For information, Orsay is about 35 mn by public transportation from station “Denfert-Rochereau” (Paris 14).
See maps on http://www.ratp.fr/plan-interactif/
Many offers for accommodation on the official website "Paris Tourism Office"
Other useful link:
All tourism Information on http://en.parisinfo.com/