The Alaska Airlines offer of 2,000 miles or $20 if your luggage arrives over 20 minutes after the airplane door opens is a super deal. I snagged 4,000 miles on my recent trip between San Francisco and Spokane. I just timed it carefully, starting my timer the instant the door opened. Luggage arrived 21 and 23 minutes after that. A quick stop at the luggage office got me the certificate. No questions, no hassle. Amazingly, I was the only person from the two flights taking advantage of the offer, even there was a sign on each carousel advertising it.
I may need to start checking bags when flying Alaska.