With regard to Premium Class for MVP Gold, I think it's only available at booking if you're paying for one of the higher fare classes otherwise you have to wait until your elite upgrade window opens. You'll likely get more miles if booking AS since they have the traditional mileage program. I've heard the JFK routes are relatively easy upgrades on AS although SEA will always be a challenge for MVP Golds...I would route via PDX or SFO would dramatically increase your upgrade chances and boost your EQMs/RDMs.