San Francisco ? No doubt a hefty portion of the $790 billion Americans owe on their credit cards was paid to airlines and hotels as families relied on the plastic to make their vacation dreams a reality.

While most of us enjoy the travel planning that entails online searches for airfares and the avid reading of guidebooks, few Americans spend as much time budgeting travel dollars in advance of departure.

Among those seeking his financial-planning services, about three-fourths “paid for their vacations with credit cards,” said Andy Keeler, a certified financial planner with Everhart Financial Group in Columbus, Ohio.

“Most people, they don’t plan. They figure ‘Let’s just do it now,'” he said. “They’ll put it on a credit card or home-equity line of credit.”

Even wealthy people are unlikely to budget discretionary items like travel, said Gary Buffone, a psychologist and director of the Family Business Center in Jacksonville, Fla.

“Very few people, no matter what their net worth and the level of their intelligence and financial savvy, do any kind of budgeting for trips,” he said.

“People who are dual-income and hard-working, they feel like they deserve the break and they’re not going to scrimp in terms of what they spend,” he said.

And they have their reasons for avoiding a budget.

“It’s the antithesis of what they want to experience when they go on a vacation,” said Kathleen Gurney, a psychologist and chief executive of the Financial Psychology Corp. in Sarasota, Fla., a provider of money-management tools.

Vacation “should be a feeling of freedom and fantasy. The last thing they want to do is sit down and make it another mundane money-management exercise.”

But given the quantity of vacations Americans take, budgeting ahead might make sense. Families take an average of 2.6 breaks annually, and that’s only counting jaunts that include a hotel or resort stay at least 75 miles from home, according to the YPB&R/Yankelovich National Travel & Leisure Monitor.

Counting big trips plus short getaways, Americans take about four trips each summer alone, according to estimates by the Travel Industry Assn. Last summer, domestic travelers said they would spend $1,000 on average for a weeklong summer trip, according to an association survey.

Yet few travelers plan for trips lasting five nights or more, according to the YPB&R/Yankelovich survey.

The survey doesn’t make clear whether travel planning includes budgeting or not — but those vacationers who set money aside in advance of their trip are more likely to enjoy their getaway, financial planners say.

“Do you want to have a good time or a guilty time?” asks John Sestina, a certified financial planner in Columbus, Ohio, and author of “Managing to be Wealthy.”

“It adds to the joy … when you come home and you don’t have those notices from American Express,” he said.