Id like to see this expand beyond just a brothel game, there could be other things you could do. Like expanding to have the third floor where you have what is called a Black Market room (You can assign up to 5 people in this) where they are selling Guns, Prostituting and Selling drugs.
Some ideas for guns
-9mm Pistol
-AK47
-M4
-Double Barrel Shotgun
-Bayonet
-
In my opinion this is something that can be made into a CrimeSim.
You could potentially introduce Drugs if you wanted to as well, Drug trip adventures in your game might give some creativity, and you could have a Drug Lab where you can craft different drugs (Marijuana, Alchohol Experiments, LSD, Ect.) If you want to take this a step further you could have your girls or guys sell Drugs in the slum, there is a chance that they could get caught and you have to pay bail (or not)
You can also pick up any drugs that you find on defeated Thugs you encounter, You also can call the Police on them and they will be arrested.
The Bank as I assume is going to be a place you can deposit the money you make in case you are worried your about to be attacked by hostile thugs, In the case that you are defeated the Bank should protect your investment from being harmed. You can donate money to Charities or Start local businesses (Just to add some interesting storylines)
Brothel Competition - You should make the story more immense with Rival brothels in the city, Competition can set circumstances where you can try to hire a girl, but then a rival offers more. You can storm the Hostile brothel with your own Army of Male and Female characters (Since I proposed a Black Market Room) The Armory will be either the basement of Top floor (Assuming that will be coming in time) You can Arm your Thugs and Train them to become Soldiers to fight for you. (Listed as Soldier instead of Thug) Soldiers have nicer Attire, Armor that reduces loss of HP. They have a boost in the security room as well.
The way this "Invasion" method would work is you have a map of the enemy Brothel after you fly a drone (Must buy off Black Market) after scanning the house you can look at a map where you click on the different rooms to begin to clear all rooms, Your Party is with you when you are Personally Clearing a room. BUT you can assign Squadrons to clear different rooms, where there is a chance your squads may win or lose depending on what the enemy your are up against has
That brings me to another topic, Brothel Defenses, Install Defenses such as sentry Turrets, Security Lasers or motion sensors or even a kennel to have K-9s to defend your brothel, There can be incidents of people trying to sneak into your brothel attempting to take your money, When this happens you will be alarmed when the room has sirens going off and a sign appears "CODE RED"
You can defeat them and put them into interrogation, where you can use Various fun toys of torture to get information, these interrogations could be what leads the story onto bigger and better things.