DL counts JFK to DEN, LAS, LAX, PDX, PHX, SAN, SEA, and SFO as transcons for lounge access purposes. See this link (near the bottom, next to "Transcontinental First Class, BusinessElite, or Full Y-Class Passenger"). Obviously a much larger list than AA. The notable exception for DL is SLC, presumably because they have no competition to worry about and more of the JFK-SLC traffic will connect onwards.