In San Myshuno Spice District, on The Old Salt House lot, I built a large combo lot that had a cafe, bookstore, gym/dance studio, laundromat, ballroom, and an apartment. I've used it as a retail lot the most, and hired a barista for the cafe when I go there. The NPC Sims wouldn't use the rest of it that well until I made some clubs that drank coffee, worked out, used the computer, etc.
I never figured out how to make the NPCs do laundry. I don't think there is a Club Activity for that, is there? I've also heard washers/dryers don't work on retail lots. I never tried using them with my active Sim as I figured I would need to have dirty laundry with me, and I don't know if you can put that in your Inventory. I don't think linen piles even spawn unless you have the machines, do they? And then there would be no point in going to the laundromat, haha. Or do the hampers fill up without machines on the lot? Has anyone actually used a laundromat in some fashion, or are yours just decorative?
I was going to use the Ballroom for a Fundraising Ball for my Charity Organizer by scheduling some sort of party on the lot after I changed it to a Bar. I wonder what type Party would be the best? I would hire a musician and bartender, stock the buffets and go around asking the Sims that were invited for donations. Later on, I would hire a DJ, for dancing. Hopefully they wouldn't wander all over the rest of the lot, which would be "closed," but I might need to remove doors beforehand. I need to play that Save and see how that goes, but I get distracted with new stuff, haha.