While I frequently use a sorta generic build (surface is a walled in area with access to the top of the wall for archers, fish and butcher industry and trade caravan, 'dirt' level is storage, first stone area is for main hall, main barracks, hospital, dormitory and some workshops, below that is primary living quarters, below that are noble living quarters, and all the way down in the magma is my metal industry).
However I have done a few where there was a 'great fort' and a 'horrible fort', separated by a set of bridges making accessing one from the other controlled. The former was opulant and wonderous, the latter was very utilitarian and functional, but depressing (and also the first area for invaders to hit). Normally I just put useful dwarves in the former and useless ones in the former (until they become useful) but spurred by another thread I have been thinking of making a death trap thing between (can you make it so your dwarves will trigger traps?), so on the paradise side are a bunch of mangled, but happy, dwarves.
Have also thought about making a similar death trap to weed out unskilled migrants, you want in you either have to come with great skill, or be really lucky (normally I just stick unskilled ones in my military with cheap armor (if any), they can serve as cannon fodder, but this idea seems much more interesting).
-MB