(Excuse the long post, I'm burning off some time while I'm waiting for something IRL.)
I'm running out suggestions I can think of that would fit the game without seeming TOO off or weird, but here's some more I guess:
1. Sex scenes that function differently instead of just the regular sex mechanics, so instead of picking a speed and going with it, you'd have some other mechanic to it, like:
1a. Having a milking machine on the milking floor where you manually tug on the nipples to milk them.
1b. Having a/your character tied up so you can tickle/spank/lick/whatever wherever you want by clicking.
1c. Enema on that one floor with all the showers, where you control the valve to fill your/their bowels with water(/cum?)
1d. Petplay floor with a super basic "Tamagotchi" mechanic where you need to drop by to feed, fuck, and wash your "pet" every now and then? IDK, I just watched a Youtube video about Tamagotchis, haha. Taking care of the "pet" is literally just three buttons that you press every now and then, only if you actually have a pet active.
2. Maybe a room on a floor (maybe the porn studio floor? Or a "VR" floor?) where you can pose your character manually, clicking and dragging their limbs wherever you want with whatever background you want.
3. Add cosmetic surgery to the medical floor? Or magical cosmetic surgery on the fantasy floor? An animation of your character's assets getting bigger via saline injections would be cool, but a black screen or a magical flash is fine too. Either way, it lets you go one size bigger than normal. Could be a whole new floor I guess, too, a surgery floor? Probably don't want scalpels or cutting though, unless you've got enough fans of that following you...?
4. Inflation floor? Pumps, valves, air, water, helium? Could also tie into #1 up there and let you work the pumps yourself. The game's already got the shape keys for the sizes too, so it's probably not THAT bad to implement. Could probably include "tattoos" with ports on the skin, or maybe a sex toy that's just a pump.
5. YOU get to be the giantess. I forgot to check if the giantess floor already lets you do this or not, though.
6. Feedee/feeder floor. Downside to this one is that people might want fat girls, but the game doesn't have fat girls or a fatness slider, so it'd have to be made, which is extra work for one (1) floor.
7. Hypnosis floor? Swirly eyes and all that. At least one gag about making someone think they're a chicken or a cat, too. Maybe you can get a hypnosis tool that lets you hypnotize anyone on any floor for a free sex scene, but you get no XP out of it.
8. Sex toy upgrades. Maybe different lubes to pick from that you apply to it? One makes pleasure rise faster. One makes your pleasure stay maxed for a little while. One makes you lose pleasure faster when NOT using it, but sex scenes give you more XP, that kind of stuff.
9. Furry floor? IDK. Could be a circus or something, heh. The return of the transformation machine? Zootopia knockoff? IDK.
10. Goth/Emo floor. Unlocks tattoos, goth makeup, and piercings. Could be a bit more vanilla in terms of sex, but I guess it could also do things like disinterested sex with one party just staring at their phone, or more pitiful/sad sex, or it could be things like strangulation and autoerotic asphyxiation or something. At least one shirt with knockoff Invader Zim on it for giggles. Probably no cutting, I imagine.
11. Add some cyberpunk stuff to the sci-fi floor. Spiky mohawks, leather jumpsuits with a laser pistol on a holster, neon goggles, etc.
12. Transformation floor? Fuck a woman who's petrified from the waist up/down, fuck a goo girl, fuck a couple furries that only growl and can't talk (who have sex quite aggressively), there's a few people stuck in vats around the floor who are half-this or half-that. Could be mad scientist themed, or "horror movie monster" themed.
EDIT: had to fix some formatting. Also, if I had to pick one, it'd be #4, I'm an inflation/expansion addict, plus there's the added benefit that it could work entirely off the game's existing shape keys. I guess it could also be "big-themed" or "hyper" or whatever, where everyone on the floor has SOMETHING maxed out. Bimbo floor?
