recommendations for thermal spa near Paris
 

Does anyone know if there are any nice thermal spas within a short (less than 2 hours, one hour is even better) driving distance from Paris? My sister lives in Paris and I would like to treat her to a day of rejuvenation for her upcoming birthday. She would probably most enjoy spending part of the day walking through a pretty town or in the countryside and spending the other part relaxing in a thermal pool, with a nice massage, but probably not a lot of fancy treatments. Does anyone have any suggestions? I am trying to recreate for her the wonderfully rejuvenating experience I had at a lovely Tuscan spa in San Casciano dei Bagni.