Thats strange because on my playthru i was only able to either pick the womans butt or breasts i was not given the opportunity to pick both on one woman individually.
The characters you're referring to are the two main characters, they currently don't yet have an hourglass option but are planned to. I was talking more specifically about other characters, for example Nylah, the character you interact with in the introduction. She has hourglass in the intro itself and in her later story.