oops... The Saint-Geran will definitely mean a high jump in prices....
Another option, a more affordable one maybe, would be the Sofitel Imperial in Flic-en-Flac which we also stayed at and this is a very nice hotel.
Very large rooms (almost 50 sq meters), excellent service, good restaurants (a bit pricy though), but this is a nice place, more of a real 5 stars level.