The difference between men and women -- at the spa level.

Here's an article about the business of spas: how do you get men to go?

Well, put some chunky, dark brown furniture in the waiting room. And describe the treatments in car-mechanic terms like "tune-up." Don't talk about pampering and caressing them. Talk about fixing them for practical purposes. And help them with the whole nude thing:

Televisions were installed in the locker rooms, to distract them from the awkwardness they feel in socializing when naked. Women, in contrast, were happy to read a magazine or chat in the nude.