I second Samsquatch on the children thing. After you play for a ton of time to get a ton of feats and the like (mainly the cheat-y one to stop the rescue because the tome is too short without) you can end up with so many kids that it takes more time to scroll through them than to beat Sonya's father (that's just me though, it always takes me forever to kill him no matter my level...).
Speaking of kids, I'd love to see more mpreg content expanded. Such as the creatures who would normally not sex up a fully male player (such as the Plush Lion or Sabretooth to name a few) to do so. Also, if we could fix the bug where the last romp in the hay gave you a baby for the new one and then you had an Alpha Husky and not a whatever because that is just really really annoying.
As for NPCs, Anthony, Ammy, Dominant Hayato and the Red Oni Lair. And Atticus. Almost forgot him since he has like two scenes....