As Republic Airways Holdings was in the process of bidding to acquire Frontier in 2009, it was also in the process of acquiring Milwaukee-based Midwest Airlines. Through the fall and winter of 2009, Republic operated its two new acquisitions as separate brands. However, to improve efficiency by better matching aircraft capacity to route demand, Republic began to intermix the fleets of the two airlines, swapping a portion of its higher-capacity planes from Frontier with its smaller-capacity planes from Midwest and vice versa. However, the move caused some confusion amongst the public, as the two brands did not offer the same amenities and did not match the amenities mentioned on the airfare. As a result, in the Spring of 2010, Frontier and Midwest Airlines announced that their brands would merge, with Frontier being the surviving brand. This was a merger of brands only—no Midwest Airlines aircraft was ever operated by Frontier, as by this time, all Midwest Airlines flights were operated on its behalf by other Republic Airways Holdings subsidiaries.
In April 2010, Allegiant purchased six Boeing 757-200 aircraft from Thomson Airways for flights to Hawaii with the delivery of the first two in the following months. In September 2011, Allegiant Air introduced the 757 into service from their main hub in Las Vegas. Allegiant later began using the ETOPS configured 757s for service to Hawaii. Fresno and Las Vegas were the inaugural destinations with nonstop service to Honolulu, Hawaii. Nonstop service to Honolulu was then added from Bellingham, Boise, Eugene, Phoenix (via Mesa Gateway Airport), Santa Maria, Spokane and Stockton. Nonstop service to Hawaii was also planned from Monterey, CA but was not actually operated. Allegiant then began to reduce its Hawaii service after determining that the extensive and costly maintenance check - which happens about every six years and costs upwards of $1 million - would not be efficient on the aircraft they flew to Hawaii.
Allegiant aims primarily to serve leisure travelers, particularly those in colder northern climates, going to warm-weather tourist destinations such as Punta Gorda, Tampa Bay, Las Vegas, Orlando, Los Angeles and Phoenix. It also serves smaller destinations that see few direct flights by major carriers. Many of the airline's markets, such as Peoria, Illinois, are served only by commuter service requiring a connection at an airline hub. In October 2009, Allegiant had competition on just five of its 136 routes.
Frontier took delivery of its first Airbus aircraft (an A319) in 2001 and simultaneously launched with it DirecTV in-flight television along with a new company livery. Frontier Airlines was the launch customer of the Airbus A318 in 2003. In mid-April 2005, Frontier officially became an all-Airbus fleet, retiring its last Boeing 737.
Frontier Miles is the frequent-flyer program for Frontier Airlines, replacing the EarlyReturns program, which existed from 2003 to 2018. Frontier Miles can be earned by flying Frontier Airlines, using the Frontier Airlines World MasterCard, or by spending at partner hotels, car rental chains, cruises, and merchants. Frontier Miles can be redeemed for flights, magazine subscriptions, and car rentals. Since February 2019, hotel stays are also part of the redemption options.
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).