Originally Posted by
amolkold
For JFK-LAX, upgrades will be tough anywhere. AA only gives UGs to 100K flyers and makes lower tiers apply with 5 upgrade stickers. UA requires RPUs (regional SWUs) for JFK-LAX. Delta includes JFK-LAX on complimentary upgrades but with a 16-person cabin, usually no one below Diamond/Platinum will get upgraded during business hours. However, a SWU puts you at the top of the list.
If you might travel from JFK to LAX at 9pm with any frequency, that would push me towards DL. They run a nonstop at that time which is IME a much easier upgrade than any of the other flights, and a free upgrade to DL's BE on this route is among the better options.