Do you intend to give AS future business or will this be a one-time thing? I don't really see the point in enrolling in MP unless you intend to accumulate a significant number of miles in the account. What would be the point. Additonally the LAS-SEA route is fairly easy to get upgrades but it's a relatively short flight and even at meal times the most you'll get is a hot or cold sandwich/wrap or salad. Really not a good use of a once in a lifetime status match IMHO. The difference between the upgradable fare and paid F is less than $100. If you have a mileage account with any of AS's partners paid F will give you a 50% class of service bonus. Just a thought.