Last week I was searching for flights on Matrix and it showed SLC-DFW-LGA as an option that was a good price and worked best for the times I wanted. DFW used to be a hub, but not any more. I went to DL.com to book it, and it didn't show as an option. I couldn't even find it as a multi-city booking. I had to call, and the phone agent managed to book it. I think it ended being two one-ways in different fare classes. I believe the return trip was booked at a round-trip fare.