Don't do another 4-player cab (you already have one).
I suggest you look at something else. A single-player cab with single joystick would be better for many games, and most joysticks have 4-way and 8-way restrictor options. A trackball cab. Dedicated cabs are best, but you could combine the single joystick and trackball into one single-player cab and tick off both boxes at once. I know you have those on your mega-panel already, but a this would be neater and better and you can then dedicate the 4P cab for multiplayer gaming.
A dedicated Shmups cab would be nice. Single player only and a vertical CRT screen would be my preference!
Driving cab is another option. However, a full cab (with cockpit) will take up a lot of room. Many people just make do with screens on a table + driving controls. Then they can easily put it away in the cupboard when done.
There are many options, especially once you start looking at alternative control systems like 49-way joysticks, spinners, lightguns, etc.
You can always come here for advice. As always, you can ignore it if you choose