Road warriors who log less than 50,000 miles a year swear Northwest is tops. Silver members report getting upgraded on half their trips, more than double the reported rate at competing airlines.

Key markets: Detroit, Indianapolis, Memphis, Minneapolis

Elite miles: Silver (25,000), Gold (50,000), Platinum (75,000)

Pros: As on partner Continental, elite fliers get automatic upgrades when premium seats are empty. Membership to Northwest's WorldClub airport lounges (where cocktails and Wi-Fi are free) is cheaper than at other U.S. carriers, and includes access to club lounges operated by all partner airlines.

Cons: No members get priority baggage handling, and only Golds and Platinums get standby services. Northwest's labor strife has hurt customer service, and the airline's fleet is the industry's oldest.