My next milestone is 55K and my go-to choice has been the upgrade certificates but I'm cuious if people are still choosing those or taking the miles. The lack of U space on most domestic flights over a few hours continues, people are not clearing HA upgrades with certificates as frequently as just a few months ago, and we still don't know how exactly to apply them to European flights in terms of fare, using the online form, etc. so I'm wondering if there is still enough value there to choose those over the miles.