Really, I don't see any reason if flying out of a certain point if the flight from that city is cheaper, depending on the carrier provided, would be rejected just for the sake of having to fly out of LAX. Texas, Florida, and Atlanta are likely to be cheaper if you wanted to fly somewhere in central/eastern North America and much of the Caribbean/Latin America for example, and flying to Europe out of the Northeast is usually cheaper. Meanwhile, if you're from outside the West Coast and won a trip to Hawaii, Australia, or Asia then a stopover at LAX makes better sense. That said, I'm not sure about class upgrades, but of course the priority goes to people who want that, and I'd imagine after a certain point if seats are left, then presumably that upgrade could be offered. If the destination you won is less than 300 miles away, then I'd honestly just drive or take the train. But it would be silly if you lived in say New York and had to fly first to LA and then back to Europe for example, and I've never heard of anyone who had to made such an odd flight based on what I've read about contestants winning.