Ended up getting that second shelf bought and setup, and straightened things up a bit.
I ended up going with the staggered setup so I would have a little extra space on top of the bottom unit to setup the iPad stand, and for stability (the top shelf is up against the wall and the mantelpiece; I didn't feel like putting more holes in the wall to actually screw it in place). It works out rather well, even if it does look a bit odd.