I jumpseat quite a bit on AA and Eagle. I've noticed quite a bit of difference from US Airways procedures. Before I begin this, I am NOT bashing AA. I am actually ready to come together as one with you.
US Airways procedures place more of an emphasis on flows rather than long checklists. This, in my opinion, is better in the fact that both heads are up and there is less distraction. At AA, the checklist is a mile long. The FO has his head down constantly. While he's doing that, the captain has the tiller in one hand and is reaching way behind him at the same time trying to reach the PA mic.
At Airways, we allow jumpseater bags in the cockpit, regardless of their seating assignment. The FA's are usually good in lending their closet for a jumpseater bag. At AA, my bag has never been in the cockpit, and the FA's nearly always refuse to put it in their closet. And stacking it on top is a big faux pas.
It seems that the US culture is more of an easygoing, laidback environment. AA seems to be more strictly business, by the book, (pardon me, but more of an anal type approach). Not bashing, just two different types of culture.
I think that there will be some major growing pains in the integration.