Remember these famous lines from the 1967 movie The Graduate? A young, confused Ben (played by Dustin Hoffman), not knowing what he wants to do in life, is poolside when Mr. McGuire, a friend of the family, says that one word to him: "Plastics."

McGuire: There's a great future in plastics. Think about it. Will you think about it?

Ben: Yes, I will.

McGuire: Shush! Enough said. That's a deal.

Don't do it! Just don't do it! Please resist the temptation of thinking a great business concept will unequivocally be a great investment.

If you, like me, love theme parks, you're tempted to want to own a piece of your heaven on earth. Well, before doing so, look at this five-year chart of Six Flags (NYSE:PKS) and Cedar Fair (NYSE:FUN). Six Flags has almost twice the trailing revenue, but Cedar Fair has been the "fun" one to own (right down to its ticker).

Today, Cedar Fair announced its first-quarter results. Although the 130-day peak operating period is just starting, two of the partnership's parks were open through the winter months: Knott's Berry Farm, close to Walt Disney's (NYSE:DIS) Disneyland, and Castaway Bay, an indoor water park that opened in November 2004 in sunny (really?) but cold (outside) Sandusky, Ohio. Overall revenues increased 7%, with the water park's attendance offsetting (and then some) the loss of approximately 100,000 guests in Southern California because of extremely rainy weather.

The bad news was that expenses were up 13% -- although that was to be expected with Castaway Bay's opening and the first winter expenses from the April 2004 acquisition of Geauga Lake (from, you guessed it, Six Flags) for $145 million in cash.

Cedar Fair has high hopes for 2005. After spending a modest $30 million to support the 2004 season, the company has spent $80 million to bolster 2005's success, with the showcase additions being major roller coasters at Knott's and Dorney Park and a water park at Geauga Lake.

Cedar Fair expects 2005 earnings before income taxes, depreciation, and other non-cash charges (adjusted EBITDA) to rise from $173 million last year to between $185 million and $195 million this year.

So, how does Cedar Fair compare with Six Flags? For the trailing 12 months, Cedar Fair has 21.7% operating margins, while Six Flags limps in at 10.8%. Six Flags has almost twice as much debt as revenue, while Cedar Fair, even after the major acquisition of Geauga Lake, has total debt that, according to most recent annual data available, amounts to 85% of sales. According to the most recent full-year financials (for the year ended 12/31/04), Cedar Fair possesses interest coverage (earnings before interest and taxes over interest expense) of 4.64, while Six Flags' interest coverage is a paltry 0.78.

Analysts see Cedar Fair earning $1.69 this year. That puts the stock at a modest 18 times forward earnings. Analysts estimate that Six Flags will lose $0.54 this year and $0.50 in 2006. Yikes!

Add it up and Cedar Fair's tale is that of a profitable amusement park operator, with great expectations for the coming year, that also pays its shareholders a robust 6% dividend.

Fool contributor W.D. Crotty owns shares in Walt Disney -- and frequents Walt Disney World. Click here to see the Motley Fool's disclosure policy.