There are always choices. AA, in particular, would seem to fly between those cities pretty nicely. Also, while I understand this is anathema to some people, when nonstop flights aren't available, you can always connect...

Mistakes happen, on all airlines, and indeed in all walks of life. I agree with the other posters; for me, how UA responds would be more important than the mistake that was made. I've had UA misroute my luggage on multiple occasions. Twice they've flown it on a different carrier to get it to an airport where it was convenient for me to go pick it up. I'll take that over my experience with PR, where my luggage was pilfered (although, admittedly, I have no idea whether or not their staff was responsible; it was during the dark days between "we'll cut the locks off of your luggage" and "we have locks that don't really do anything because the TSA has a secret key"), or my experience with AS, who snapped at me that "this isn't Federal Express" when I asked where my bag was.