Did you try to get rebooked on the AA flight yesterday at the time of cancellation?
Yes. There weren't any seats. Spent 4 hours on the phone with agents last night to ultimately find one seat on this UA flight tonight.
Also, how much time difference are we talking here (what time was the original flight & what time is the AA flight)?
I think you'd really have to press an agent to book you on AA if you're only going to save a few hours, especially since you've already accepted what was probably a 12 hour delay.
4 hours, gets me to my destination in time for a dinner tonight that I am supposed to be at