Felwithe, Kelethin, Freeport and Grobb bankers can all be accessed using nothing but invis and F9 to move the camera around a corner. If you need a demonstration hit me up here or in-game and I'll be happy to help you out.
If, however, you're trying to just chill in goodly cities,
Here is a decent guide from the perspective of an Iksar. Good luck!