I think we have some decent areas that allow evil to exist already, though some could use a small change or reminder to help shift the server culture.
Guldorand is a very gray area which allows for evil and non-evil to exist. Since its birth I've seen the Charter successfully keep the good leaning attempts a little more tame and serve as a prime example of how the stark black and white split of good and evil can be kept at bay by server setting; which was mentioned as more realistic to the Forgotten Realms.
This required the occasional DM to step in and have a meeting/post a reminder by the Founder's Council, or other small changes. I also think changing the Eagle's ownership was a huge improvement. These little shifts with Guldorand, even Andunor from it's Hub Hellball days, have made the server culture itself shift, something I think could be used to improve the culture of other places, such as Sencliff.
Sencliff could be another good gray area. It is heavily favored towards its inked inhabitants as far as access, which I don't think is necessarily bad. I really enjoyed it once upon a time as a non-sailor, non-pirate between various aligned characters, yet I've chosen to spend time elsewhere due to the ease of leaving and running into the mentioned gank squads-- which I hear continues after all these years. If a gradual shift is made and it was allowed certain settlement PvP rules regardless of being a settlement, I could see the gank squads being less of an issue and the possibility of more people becoming comfortable hanging out or passing through there.
Sibayed...another gray area, less a home but somewhere to go sometimes... No monster races allowed and the merchant league tells troublemakers to "get off my lawn". Although some of the writs existing elsewhere means you can skip visiting Sibayed altogether to do writs, so an excuse to go there other than check for homes and shops, might increase foot traffic. My own suggestion would be improving/increasing the size of the arena and maybe adding a second entrance/exit. I've seen more fight events being held out in the desert rather than in the arena or they've fallen to Dis.