Some new feature ideas:
Lingerie Night - A one night a week bar event where the girls wear lingerie instead of their usual dresses. Creates an opportunity to see the girls wearing all of the lingerie which you have only seen them wearing either in their room or in sexts that they have sent you. Also creates a new opportunity for bar events which can only be triggered on this night. Also, maybe the perfect setting for a game of titty fighting? Or maybe titty fighting should be a pool thing.. I dunno. Anyways, it seems like it could be a cool thing to set up a super sexy one night a week thing like this.
A tits upgrade for one of the smaller girls? - This seems like an obvious thing to do at some point so I wouldn't be surprised if it's been suggested in this thread many times already. One of the smaller girls, like Sara, Brenda, Lacey, Renee or Delizia (Del would be my choice) have a story arc in which they express a desire for bigger tits and the MC and Joy make it happen. It's an opportunity to create a story and big quest arc for one of the girls, maybe reveal a little more about the story line since it involves Joy's science madness, it's an opportunity to involve Sara and Daniela in the lab and of course it's an opportunity for huge tits, which this game is clearly focused on. It's also an opportunity for the game to lose one of the few girls with regular sized tits so some may complain but, like my mama always said, big tits are the best.
I realize that this would require an enormous amount of work because all of the girl's scenes would need to be redone with the new tits.. so I guess Darkhound would have to craft some pretty amazing tits for it to be worth it.
Make tasks and quests a permanent part of the UI that you can see at all times and hover over for hints just like in the phone. Make it collapsible to reduce clutter when you don't want/need it. (I see that something like this may actually be added in 0.3.1.0)