Rata Sum is filled with little places to go and halls and all kinds of neat places, but only the first two floors of the city are really utilized. The third floor, the bottom one, and in my opinion the coolest one hands down, is a ghost town. I am literally the only one down there at all times when I go down just to admire how cool it is down there.
This doesn’t have to be top priority, but some added things to do, maybe NPCs, whatever can make the bottom level of Rata Sum more lively, and make people want to go there, would be awesome, especially for people like me who love hanging around down there.
While you’re at it, maybe take a look at other places in cities that are ghost towns?
I think all the cities could use a little umph to be honest, and lessen some of the lag in LA! :P