I'm curious to know how many people actually go in and select a higher fare class when booking a ticket? There's so much talk on here about fare class, value to the airline, upgrades only on certain fares, etc. I'm specifically talking about domestic trips, since I know people probably do it in order to use SWUs.

But who honestly does a search for a flight, finds availability in LUTVX and then says, no, wait, I don't want that fare, I'm going to go back and buy a K (or higher) fare on this same exact flight so I can pay more?

(Maybe that could happen this year with MQD's, but I still think it's a long shot).