I had a reservation and a confirmed seat. I get to Pearson Airport (Toronto Int'l) 2.5 hours before departure. Get my boarding pass from the Kiosk and on seat assignment it says "Gate". WTF, I go to customer service (1 hour wait) and they say I have to deal with it at the gate, which won't open until 45 minutes before departure. Turns out some school(s) had reserved their seats on-line the night before for Spring Break to Los Angeles. They had overbooked the plane. So I got bumped but got another seat six hours later. In my million miles or so of flying, I've never been bumped before.
For my troubles, they are sending me a check for $800.
I would have arrived at LAX about 4 PM and faced a Friday rush hour drive of 2+ hours, and maybe have gotten home by 6PM if I was lucky. I arrived at 9PM and was home in about 45 minutes. So while it sucked hanging around the airport for six additional hours, in reality I actually got home about 4 hours later, so $200/hour ended up being sort of OK.
Moral of the story, check-in online the night before, even if you have to cough up a few bucks at the hotel business center to use their computer and print out your boarding pass.