To bring in another thread, but not to derail, my taste for running urban campaigns very much informs my use of floating objectives. I agree with @Lanefan that cities are an ocean with a teaspoon proposition when it comes to any notion of 'fully prepped' so I've had to do things differently. What I usually do is hard plan some major objectives, the ones which all the other clues, hints, and rumors index. Then I semi-hard plan some second tier objectives and encounters based on what I think likely, and under that I usually have a whole mess of NPCs, rumors, mini-encounters, clues and other stuff like that in various states of soft planning, including exact location.
Depending on how the players engage with the initial hook and what direction they look like their heading I'll scatter breadcrumbs out along that path, again, in various states of hardness. The prep is there, and I have many times more info planned than I'll need, but I need to be flexible enough that no matter what the players decide to do I can pave a road far enough out ahead that I can avoid last minute deus ex machina. The biggest part of my decision making is actually the players' decisions. Part of the way I run is to let player decision making determine exactly how the fiction plays out. I can't control exactly how that's going to go in any game, but especially in a urban setting, so past a certain point I don't even try. If the players have a plan and put together the breadcrumbs in a particular way, then I'l take that and run with it. Not entirely, but let's call it for a given value of 'correct' with the value of incorrect being put on where it wil be the most fun to have them be wrong in their initial read on what's going on.
Depending on how the players engage with the initial hook and what direction they look like their heading I'll scatter breadcrumbs out along that path, again, in various states of hardness. The prep is there, and I have many times more info planned than I'll need, but I need to be flexible enough that no matter what the players decide to do I can pave a road far enough out ahead that I can avoid last minute deus ex machina. The biggest part of my decision making is actually the players' decisions. Part of the way I run is to let player decision making determine exactly how the fiction plays out. I can't control exactly how that's going to go in any game, but especially in a urban setting, so past a certain point I don't even try. If the players have a plan and put together the breadcrumbs in a particular way, then I'l take that and run with it. Not entirely, but let's call it for a given value of 'correct' with the value of incorrect being put on where it wil be the most fun to have them be wrong in their initial read on what's going on.