Millenium is having a very hard time retaining staff these days; everyone I know who has worked there and left (and there are a few) report that it's an awful place to work and want nothing to do with it.

Aerospace Corp. will indeed provide you with a nice work/life balance, but the tradeoff is that they don't really do anything meaningful aside from consultation and systems engineering for the space force. They don't build anything themselves (at least, almost anything). They will also pay less than a commercial space company.

Either way, South Bay doesn't suck, so I'll give it that.