The Prone Bone position is actually a pretty sexy position. 
2. We have got face to face cowgirl position with the elf, but the side view version with this position with any other other girl would also be sexy. 
3. The witch can provide special services after we have progressed with her story in the future updates. Like: A handjob, blowjob(already we have), Different vaginal and anal intercourse. We may even have a threesome options with any other girls.
4. The journal should have quests sorted out by girl's names and when quests are completed, there should be a tab where we can see our completed quests.
5. A affiliation bar ( relationship status) should be present. The more we have affiliation towards a girl, the more we can romance and unlock new sex scenes.
6. Cunnilingus positions.
7. Easter eggs girls. For example, let's say on Friday a girl may appear on any location within the map. We can talk and get side quests which may unlock more new sexual scenes. But only once or twice.
8. A percentage bar in gallery. It may tell us how much we have completed or unlocked sex scenes in the gallery.
( ╹▽╹ ) I hope some of my ideas are good for the development of the game.
P.S. The images present are just for reference.