The latest merger plus crowded planes mean more hassles. By Anne Kates Smith, Executive Editor June 18, 2010 Airline passengers, brace for higher costs. United Airlines' merger with Continental Airlines (assuming it goes through) could boost both fares and fees. Continental will probably raise its fees to match United's, says George Hobica, of Airfarewatchdog.com. And Continental will likely adopt United's recently announced unconfirmed same-day standby fee ($50 if you board successfully).Competition from low-cost carriers will keep fares from soaring. But it's a good bet they'll rise on nonstop routes between the two companies' hubs, for which competition is nil -- from Newark, N.J.,to Los Angeles, say, or from Houston to Denver. Some hubs may be retired -- service to Cleveland may well be cut back, for instance. Frequent fliers are expected to be able to combine awards from both programs. But if United's rules prevail, your miles will expire after 18 months of inactivity. Spirit Air's new $45 fee for carry-on bags ($30 if paid in advance online) takes effect August 1. It applies to bags stowed overhead; a bag that fits under the seat is still free. Lawmakers in Washington cried "skyway robbery" and threatened to ban the fee or tax it. But New Yorker Peter Ostrovsky, 47, a Spirit Air customer, is unfazed. The fee "sounds a little excessive," he says. But with enough awards points for three round-trip flights to Fort Lauderdale, Fla., to visit family, Ostrovsky isn't complaining -- he's just traveling light.