Don't underestimate the potential to grow your women's member base by designing for the female demographic.
We studied the women's only club models, the boutique gyms, and the the better sameness models for cues regarding design for the female demographic. For the most part it's poorly executed design. The strategy is typically a toned down version of the men's locker room, paint being the common denominator of change.
Our design for the women's locker room (image above) at Mid City Gym illustrates a beautiful design tied to the brand... while telegraphing "gym," without being feminine.