Thanks for all info so far. Just a quick question, is 45 minutes enough time to change planes at Chicago if DD took the 1.05pm AA flight from LAX which mrwunrfl has mentioned. It looks the one to go for but the AA site does have a warning about the connection change, I presume this is because of the limited time.

45 mins is usually not enough time at Ohare. When is the trip? Weather delays and congestion are always an issue - it is a VERY busy airport.