Just because a billboard sign promises a great room rate at an upcoming exit doesn't mean you can't do better.

Maureen and Bill Palier saw firsthand how hotel prices fluctuate during a road trip across North Dakota to visit relatives. The couple stayed at the same hotel twice -- Saturday on the way out and Wednesday on the way back -- along the 12-hour drive. Everything was pretty much the same, except the second night cost $50 more.

The manager's explanation: Booking the visit in advance and online had garnered the better deal.

Experts agree that planning ahead is critical to unlocking the best on-the-road lodging deals. "Many chains will push the price up as it gets closer to the date of booking," says Tom Magnuson, a former owner and manager of several Best Western-franchised hotels and now principal of Magnuson Hotels, a company representing more than 450 independently owned member hotels.

"You can always get a little peace of mind knowing you've gotten things nailed down," he says.

Those members occupy an industry jam-packed with recognizable names. "There are more than 300 hotel brands in the U.S. today. We're in the hotel business, and we can't name them all," Magnuson says. Industry growth has led to a blurring of brands.

"There isn't 10 cents' worth of difference among the major chains, as they all try to outdo one another," says Bob Jones, a frugal-travel expert who writes The Smart Travelers' Corner column for OneTravel.com.

Jones, who says he may get in trouble for that statement, offers the example of a Sheraton in Oklahoma literally changing places with a Marriott. "No, they didn't move the buildings, just the signs!"

Chain hotels, Jones says, can be:

• Owned and operated by a chain.
• Not owned, but managed and operated by a chain.
• Neither owned nor operated, but franchised, by a chain.

What that means for pricing: "Chains like Days Inn are primarily independently owned and use a common reservation system. They may have far more fluctuation in rate than Marriott, which might make special offers systemwide, like 'Kids stay and eat for free,'" says Laurie Borman, editorial director of atlas publisher Rand McNally, which features online road-trip-planning tools and tips.

Frills or not?
The first step to snagging the best lodging deal on your next road trip is to identify your expectations. Nearly all travelers expect "a hot shower with decent water pressure; a clean, quiet, comfortable bed; curtains that shut out light; and a safe and secure room," Borman says. And most interstate chain hotels have those basics.

Those looking for more -- from a restaurant onsite to a workout facility to get the post-drive kinks out -- will also find chains that appeal, she says. "People have started to expect a lot more in hotels than they used to because they are traveling more and know what's out there."