Good input from alot of folks.
In keeping with the "make it personal" theme mentioned, I do:
1.) Make sure some NPCs just hate the PCs. Some will have reasons and some just won't like the way they look. Interactions will vary based on NPC and PC power levels, etc. They will go out of their way to make sure the PCs time spent in town is awful (a good reason to get out of the City every now and then or go into a Dungeon!)
2.) Have some NPCs just Love the PCs. See #1 above. They will go out of their way to make sure the PCs want to stay in town (someone to fence magic items and treasure off to for good prices? someone who heals them randomly for free when they can; or even someone who just has an encouraging word)
3.) Have various folks in the city who recognize the PCs as tools (some for nefarious means, some for benign) and who arrange for the PCs to carry out missions, not always knowing who the ultimate power is. PC/mercenary figures give powerful people (or those with some extra cash) means to "get around in the city" without "getting around".. if ya know what I mean.
Let the PCs decide how they will react to these 3 groups, and then milk it for campaign ideas from there. If you let players forge their own alliances/vendettas they will usually build the campaign for you in some ways, and along a path they desire.
In keeping with the "make it personal" theme mentioned, I do:
1.) Make sure some NPCs just hate the PCs. Some will have reasons and some just won't like the way they look. Interactions will vary based on NPC and PC power levels, etc. They will go out of their way to make sure the PCs time spent in town is awful (a good reason to get out of the City every now and then or go into a Dungeon!)
2.) Have some NPCs just Love the PCs. See #1 above. They will go out of their way to make sure the PCs want to stay in town (someone to fence magic items and treasure off to for good prices? someone who heals them randomly for free when they can; or even someone who just has an encouraging word)
3.) Have various folks in the city who recognize the PCs as tools (some for nefarious means, some for benign) and who arrange for the PCs to carry out missions, not always knowing who the ultimate power is. PC/mercenary figures give powerful people (or those with some extra cash) means to "get around in the city" without "getting around".. if ya know what I mean.

Let the PCs decide how they will react to these 3 groups, and then milk it for campaign ideas from there. If you let players forge their own alliances/vendettas they will usually build the campaign for you in some ways, and along a path they desire.