I think this game could really use some ways to reduce the micromanagement, without stripping control away from you. Case in point, despite the fact that you typically control many girls, there is no way in most cases to deal with all of them at once. That's why it would be nice to be able to select multiple girls and perform most actions with them. There is a lot of tedious micromanagement because this can't be done that really doesn't add anything to the game. However if its easier I think just adding more buttons like "release all girls" would be fine as well. I would put a small "all" button next to the main ones though, like brand slaves for example, to avoid taking up too much interface real estate.
The main area I think really need to be done in regards to select all/multi-girl selection is the fire girls one, as you constantly get random free girls through gameplay that you just don't want. Because there is a confirmation every time you fire a girl, it can take five minutes to deal with twenty something girls you have collected from business owners' not paying. This has lead me to avoid taking over business all together just so I don't have to deal with this constantly, and while the girls can be left in the dungeon technically, scrolling through a hundred girls to get to the ones you sent to the dungeon really isn't an acceptable solution either.
Most of the interface works well though, but this part really is quite annoying.