March 15 and 16: IRISA (INRIA Rennes Bretagne Atlantique), Campus de Bealieu, Rennes, France
There will be no conference hotel in Rennes. The workshops will take place on Campus de Beaulieu (March 15 and 16). Hotels (list of hotels) in the center of Rennes are convenient since there are direct buses that link the centre to the the campus (see the map on bottom). More information here
A list of accomodation available in Rennes is available here
The main conference will be held in Saint Malo on March 17, 18 and 19. There are conference hotels in Saint Malo. You can book a room on the conference registration page.