Originally Posted by aztimm

Since you're not on one ticket, I don't think TSA will let you back into T3 without a valid AA ticket. Of course with as much time as you have it might be worth a try. There is a BA lounge in T5, and depending who you are flying, you might have access to other lounges over there.
While the Flagship lounge is nice, I'm not sure it is worth all of the effort you'd need to go through to visit.