Something that I just realized is missing: For profit slave training.
Since we've all played Free Cities you know what I mean. You take a cheap, disobedient, annoying slave and throw time & effort into turning them into an ideal servant. Then you can sell them for a huge profit (if you max you personal training skill, you can easily profit $100K or more of even just one slave, given long enough).
Here, however, the price difference in a newly captured abolitionist and a devoted mind-puppet is maybe 25%. Plus training takes forever. It can seriously take literally hours of real world time to max even one skill on a slave. Worst of all, there are no player skills that can change this. None of the trading, slaving, military, etc skills we know from FC are here.
I think that this should be a pretty easy add, as mostly it's just copying stuff that's already been done elsewhere and just tweaking it a little to fit this game better.
So let's look at the problem:
#1: Lack of training furniture types. For skills, there is only one type of furniture per skill. Even the sauna only has two types of furniture - your choice is between the 1 point version and the 2 point version. Office torture racks come in level 1 or 2 as well but that's it. Everything else is one size fits all, and that size is soooooo slow. Considering that having a shitton of money can let you buy solutions to all other problems (big fleets, big factories, lots of menials, etc) that there aren't any super-powered training stuff for the ultra-rich seems like an oversight.
#2: Lack of player skills in the game. Have your avatar get involved and learn stuff, too. Throw money into classes to learn things, just like in FC, that improve your overall performance. Not just slave training, either. Military skill to make your fleet more powerful. Trading skill to increase profits from businesses. Just throw some bookshelves or equipment into the office and spend your non-fucking time more productively. Research could also be a skill if you ever decide to create a tech tree and the mechanics for that. And if you don't want to bother then just sit at your desk and "focus on business" - learn nothing new but increase your general income overall.
#3: Stealing an idea from Tropico, if your avatar heads into a room they can act as an overseer even if you haven't appointed one. Give a boost to whatever the room does. Ships repair faster. Businesses make more money. Tourist stuff becomes more appealing. Slaves learn faster in school. This would mean actually being able to move your avatar, of course, but honestly, that could be implemented very easy. Like "Hold shift while left-click to choose destination" easy.