That's how I do cities as well, I make the whole layout then place my perfect lil story buildings in appropriate places (butcher, haberdasher, baker, furrier, etc). It's very OCD but I think, on some level, all of us here are a bit obsessive about our babies. You can tell a finely crafted and thought out town from one that's just plopped down and that's what makes for a fine map...that loving care and attention to detail. Of course, once you're finally done with it you feel like you've been running a month-long marathon so you're totally burned out and spent and your next effort isn't quite so good. But after a while you get your mojo back and things are good again.