Originally Posted by MapleLeaf93

Never actually tried it myself, but I believe another option to secure an F upgrade at the time of booking if U space is available but you don't have status is to upgrade using miles. I believe it's a flat 15k per person regardless of route. So whether you're booking a SEA-PDX puddle-jumper or a SEA-HNL trans-Pacific, it's the same 15k to upgrade to F. You have to book into a minimum fare class (the cheapest available will be automatically selected for you if you specify the "Mileage" upgrade option), though I don't know exactly what that minimum is. I'm guessing it's M, so it'd be equivalent to the minimum fare class required by 75k and 100k members to secure an instant upgrade to F.