Originally Posted by
dukerau
The Premier gets a domestic buddy pass. You basically get the cheapest itinerary available to choose from, with the caveat that Delta is never an option. So if your preferred itinerary is the cheapest (or among the 10 or so cheapest) you have a good shot at being able to book it. This means that nonstops are often off the table, but not always

. I recently almost used mine for a transcon direct flight but they didn't have the exact flight I wanted so I used US Airways companion pass instead (Citi Premier / Spirit had 5 of the 6 direct itineraries that day available, but I needed that 6th one)
Worth noting that if you call, they're able to book you on a Delta flight as long as it's the cheapest. It seems that SkyTeam airlines are blocked from showing up on the site but the agents still have access to them.