For R girls, maybe a randomizing traits, so you can guarantee that they will a that type of trait, but not which one. Like, if you don't want a character to be a "teacher" but you still want them to have a job/past. or random size of boobs, etc.Also being able to change what size of font in used would be nice. Currently I find the font too small for how far back I usually sit from the screen. I'd also suggest a way to know in game how many items can be worn in each slot. And more slots (like rings and earrings, or gloves and armbands. stockings and underwear) while possibly reducing the number of items that can be worn.
I would also prefer to be able to navigate from/to all my building from either my main page/brothel or a slide down/tab menu of some sort. Rather then needing to go to the map each time. Or if you go the map navigating route, put the names onto the map, to make it easier to keep straight. (memory isn't my strong point.)
I like how customization the game is. I don't like how much time it take to edit those files since everyone has moved to single girl/item per file. (thus my "random traits plz"). only mentioning this in case you decide to make a girl/item editor for the game. The ability to combine the files would be nice, in addition to the current one's ability to split them all up.