I disagree with you (respectfully, of course!) - I think FB is one kind of platform (with more stupid policy decisions & flip-flops, in part because it's mostly the creation of a single still-immature human with a particular ideology) and LJ is another. LJ is indeed oriented to longer posts - it's a *journal* after all. FB is more of an aggregator, or so it seems to me.

I'm curious to see how Google+ works into the mix of it all!

I cannot imagine a platform that would be all things to all people, so I'm glad that B is on Fb and that way your household has both these platforms covered.