Is there any reason to check in on-line ahead of time with an airline like Delta? I'm very familiar with Southwest and the reasons for checking in on-line ahead of time with them, but since we have seats assigned with Delta, I don't see the reason for doing so. But, perhaps there's something I'm not aware of. We've flown SW for the last 5 years, so I'm fairly clueless about the other airlines, but Delta surprisingly had the best price for our return flight in March.