$1500 for a paid upgrade to E+ that earns ~20,000 miles

20,000 miles are worth, in my book, 1.5c per mile, so the miles are worth $300

So then you can take the miles part out and it "costs" you $1200 to fly E+. Since you'll spend around around 40-50 hours in flight, it means it will cost you $25/hour. Or to put it another way, $600 each way to upgrade to E+.