buy Business fare or wait to upgrade at checkout or airport checkin (day of flight)?
I'm wondering if there's any better strategy to go ahead and book a coach one-way ticket and then either pay for an upgrade to business class at checkout if I see the flight is very full (and might not get an empty seat next to me) or take the chance that I'll get prompted to buy an upgrade at the airport on the day of the flight or when I checkin 24 hours before?
Thanks!