Well, you won't have to miss all that right off the bat if ever:
US - it will stay as a subsidiary of AMR until a single ops cert is issued by the FAA, most likely a year or more. But there will be changes as US/AA mesh operations before integration.
PHX hub - retained for minimum of 3 years per the agreement with DOJ.
DCA Club - probably kept until gates are all together though likely to be AA club as long as 2 concourses are in use.
Staff - most will still be around although some may be working at a different station.
Free flight status onboard - I'd be surprised if AA doesn't already have that but Go-Go is certain to allow access to AA web site for free.
Jim