For the base itself I'd maybe simplify it a bit. It seemed a little maze-like with all the doorways and halls.
I'd also move that central walkway going right over the point, it seemed a little strange to have a cap point right under it. Maybe do two walkways around the sides going over the other two doors on the lower level instead and block off coming straight out of spawn with glass or something (even more like Badlands, I know). A crude visualization:
And I'd add another route from 2nd to mid, around here:
It felt kind of funneled-in there.
Mid point is nice, if a little boxed-in. Maybe add some large windows in the two buildings on either side?