I have a UA flight from LAX-IAH-CUN on Sunday. I have zero miles toward premier right now -- although I will earn on the outbound of this trip (return economy saver was purchased with miles.) i have about 5K in MP miles showing in the account and could probably dig up a few more. Is it worth a phone call to see if I can get a seat upgrade from LAX-IAH gratis or with my meager miles? It is unlikely I would use (nor do I have) 25K miles + $125 for an upgrade, as per their website. Is it just pure naivete to think they give away anything for free? Is there another way to ask UA besides their standard reservation phone line? Should I try in person when at the gate? Thanks, in advance.