In November 2012, Frontier started low-frequency service between Orlando International Airport and Trenton–Mercer Airport near Trenton, New Jersey, which, at the time, had no commercial service. Frontier later expanded service several times from Trenton, and as of June 2016 services 11 destinations. Frontier currently bases three aircraft in Trenton. Trenton Mercer Airport lies roughly equidistant between Philadelphia International Airport and Newark Liberty International Airport.
On September 9, 2014, Frontier introduced an updated livery, as part of a rebranding that saw the spokesanimals' roles increase. The new livery reintroduced a green "FRONTIER" typeface to the fuselage, featuring the stylized "F" designed by Saul Bass for the original Frontier in 1978. Each aircraft features the name of the animal featured on its tail near the nose of the aircraft for easier identification. Currently about twenty five aircraft in the Frontier fleet feature the new livery.
In March 2010, Allegiant purchased six used Boeing 757-200 jetliners as part of plans to begin flights to Hawaii, with deliveries from early 2010 to the fourth quarter of 2011. It gained the approval for type with the FAA in July 2011, and then worked with the FAA to obtain the appropriate ETOPS rating in order to be able to serve Hawaii. Allegiant no longer operates nonstop service to Honolulu from Las Vegas.
Like Ryanair, the low-cost airline founded by the Ryan family of Ireland, who also have invested in Allegiant, the airline seeks ancillary revenue to supplement ticket revenue. These ancillary fees include those for checking luggage, carrying on luggage (other than a small personal item), buying food and drinks on board, obtaining advance seat assignments, and more. Allegiant CEO Maurice Gallagher said in 2009, "We collect $110 from you at the end of your trip. If I tried to charge you $110 up front, you wouldn't pay it. But if I sell you a $75 ticket and you self-select the rest, you will."
On October 31, 2017, the final 757 was retired from service, leaving Allegiant with only their A320 Family and MD-80 series fleets. In November 2018, the last MD-88s operated by Allegiant were retired, with Allegiant now operating an all-Airbus fleet. The move to the newer all-Airbus fleet has allowed Allegiant to benefit from lower fuel and maintenance costs, as well as operate in some airports which could not be served by the MD-80s.
On July 1, 2010 Allegiant returned to Long Beach Airport (LGB) in Long Beach, California having previously served LGB with DC-9 jets with nonstop flights to Las Vegas (LAS) and Lake Tahoe (TVL) in 2000. The airline also intended to fly from Bellingham International Airport and Stockton several times a week; however, there is no service at present flown between these two cities although Allegiant continues to serve Stockton with flights to Las Vegas, Phoenix/Mesa and San Diego. In November 2011, Allegiant closed its Long Beach facility and consolidated all Los Angeles area flights at Los Angeles International (LAX).