So far I've been putting the bedrooms in the same place: below dining rooms which are below the workshops which are below the entrance. Only differences are that I just go a few floors down instead of to the bottom and that they look odd since they are made around the 'fun' areas (since the second I see it I wall it off. A few forgotten folks showed up but had no way to say hi to my dwarves.
Now that I've gotten used to burrows though, and once dwarf therapist is updated, I'll probably be more organized and just lock up the 'main workers' in their own burrow with a bedroom, dining room, and workshop then just make dorms for the rest until they prove themselves worthy for something useful.
As for my current group, I need a new idea for my bedrooms since a Dwarfy accident managed to send half a lake into the bottom of my fort, flooding the lowest area (no one was down there, but that's where the latest batch of bedrooms were going). I'm currently tempted to turn the floor above it into a dorm, Channel enough of the flooded rooms to get the water level down to 4 then make that the new barracks (the 'accident' was based on me trying to make a swimming pool-styled barracks above ground anyway
).
Now what REALLY changed was my metalwork. It's now a good 50+ floors down (with a single mine shaft winding around caverns) and running on magma. Now if I can just find some iron, or bronze, or SOMETHING to make weapons and armor from I'll be all set.