Originally Posted by
clubeurope
Alternatively, you can check the reward seat availabilities online for your flights, and book your tickets afterwards. Then you request for an upgrade online, which should be mostly instant. I say mostly instant because it'll take them a bit of time to reissue the tickets in the new travel class (which was 20 minutes in my experience).
FWIW I talked with MPC about this when I did an upgrade a few weeks ago. They made it very clear that that there were separate buckets for full redemption and upgrades. While it is certainly possible -- maybe even likely -- that both buckets would have availability on a fairly open flight, they caution that it is not always the case. There could be full redemption seats available, but no upgrade. And vice versa.
The website only shows full redemption availability, not upgrade. Because of their warning, I followed what I described above. I did try to use full redemption availability as an indicator, and it worked. I hate calling in... it's generally a long wait and a colossal time sucker compared to online transactions. But for me, I wouldn't book any ticket where I intended to upgrade without confirming with MPC.
Of course, you need an "R" ticket to upgrade, and that is refundable with a $100 penalty, so it's not a huge risk.