After reaching the max amount of workers/spaces available per each business, you should be able to keep hiring workers but they would be more powerful than the old ones. Kind of like a prestige system for the workers. And for places like the farm and the pool and the hotel, you could upgrade the facilities.
Great game btw!
Oh, also, it would be nice to see what each of the classes do. Such as a class name and what their benefits and downfalls are. I see that you have an animation for the gold going to the gold stash, but you should also show the xp going up there as well. I love this game so far! Great work!