For the moment, though, Disney is taking a pause in spending, while Comcast-owned Universal Studios is doubling down. (Comcast is CNBC's parent company.)
Universal plans to expand the Harry Potter franchise and add attractions totaling more than $1 billion.
"Universal really has a lot of momentum," Harrigan said. "I think five years ago Universal got some overflow from Disney parks, and I think now it's almost like they're helping each other. ... They're more 'frenemies.' "
The only business coming up all wet is SeaWorld Entertainment, which reported a 9 percent drop in attendance last quarter. The company has blamed part of that on poor weather. Many analysts expect a better second half, but there are concerns that a new documentary about orcas in captivity could keep visitors away.
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Still, overall, as Labor Day and summer recede, it's clear that Americans have been willing to make the big investment and spend a day, or a week, having some fun.
"I think the consumer is getting conditioned to $4 and change for gas," said Ouimet of Cedar Fair.
He is now preparing for the second-most important time of the year for theme parks: Halloween. For example, the company will add six new haunted mazes to transform Knott's Berry Farm in California into Knott's Scary Farm.
"You've got to remember 80 or 90 percent of the people are repeat visitors," Ouimet said. "They need something new."
—By CNBC's Jane Wells. Follow her on Twitter: @janewells