Rick Seaney, CEO of Farecompare.com, said ticket prices would likely climb in many cities if the two airlines merged.
"What drives the price of tickets mostly is competition, and what you're basically doing is taking another person off the board with competition," he said.
But travelers in North Texas might not see major price hikes because neither United nor US Airways have a big presence in the Metroplex, Seaney said.
But frequent flier Susie Wong said she doesn't want fewer choices.
"I think healthy competition is so crucial," she said.
Seaney said North Texas' hometown airlines -- American Airlines and Southwest Airlines -- are likely watching developments very closely.
Southwest said it is "committed to competing vigorously" against any new airline. And Seaney said the carrier might even grow if there is a merger.
"They get a better chance to steal some market share in areas as the other airline contracts," he said.
Things may not be so rosy for American, which would be bumped down to being the world's third-biggest airline. It used to be the world's largest airline before Delta merged with Northwest.
"The problem is, American can't find a dance partner," Seaney said. "I think everybody wants to consolidate to some degree, so they're the odd man out."
"We do not feel compelled to participate in consolidation, but we will be watching developments closely," American CEO Gerard Arpey said. "Fewer airlines may be a good thing."
Seaney said the carrier is big enough to fly solo, but it would need its Oneworld alliance with other airlines more than ever.
"Those alliances are super important to moving traffic worldwide, because that is where the growth is," he said.
NBC DFW's Brian Curtis contributed to this report.