Frontier Airlines DEN Terminal +1-888-839-0502 Standard and premium seating, including Stretch Seats with more legroom, are available on Frontier Airlines DEN Terminal. While random seat allocations are free, passengers can choose their seats for a price when making reservations or checking in. Families are able to select seats together, and Frontier Miles Elite members are eligible for free seat selection. For More : https://www.terminalfind.com/frontier-airlines/frontier-airlines-den-terminal-denver-international-airport/