Sometimes you learn the lessons of high-tech business travel in the strangest places. Even in your own backyard on a torrid Fourth of July weekend.

As I struggled to keep my tomato plants hydrated using a low-tech watering can, two women with strappy sandals and big-city sensibilities appeared and inquired about hiking in the mountains surrounding my flyspeck country village.

"The trails aren't marked, it's getting dark, and you shouldn't try to hike in those shoes," I said.

"We came up from [New York] on the train on a whim and thought it would be fun. Maybe we should just get a hotel room for the night?"

"Good idea," I said. "But the problem is…"

"Oh, no problem," one of them said. "I have this!" She flashed her iPhone at me. "All I have to do is look it up. I get all my travel information from this."

I didn't see the Strappy Sandal Sisters again, but I know what their iPhones would have told them. My village has three inns with a total of just 24 rooms, but there are nine big chain hotels clustered around an Interstate exit just 10 miles away. What their iPhones weren't likely to tell them? All 24 rooms in my village would have been sold out long ago, the train doesn't stop anywhere near the Interstate exit, and taxi service is nonexistent.

Moral of the tale: Don't come to my neck of the woods without the right shoes, and don't expect high-tech tools to solve all of your travel problems.

Tech tools have simultaneously made travel easier and more complicated—and made travel more essential and less necessary. And business travelers created the market for a slew of high-tech devices: Who but us needed portable computers, transportable digital audio and video, and mobile devices that allowed immediate communications with anyone, anyplace, anywhere on the planet?

But the tricky part of the equation is that the rules of managing both travel and high-tech change all the time. There is no immutable "truth," only an endlessly nuanced and evolving set of procedures that get you to the next improvement, the next adjustment, the next must-have "killer app." Here's what matters now:

Less Gear Is More Practical

We may never get to the fabled "convergence device" that allows us to use one convenient piece of gear to do everything on the road. But that doesn't mean we should carry a paratrooper's stash of gadgets to do our business remotely. Do we really need to carry a notebook computer and a netbook? Is carrying a Mac laptop and an iPad logical? Why schlep a music player, a book reader, a mobile phone, and a PDA too?

The "simple" solution? Take two and no more. I would suggest that a good, current-generation smartphone—a BlackBerry, an iPhone, or the equivalent—can handle all of the functions you want accessible in your pocket or pocketbook. To varying degrees, of course, they'll all make calls, do email, and texting, surf the Internet, play music and video, and handle other media. They all have built-in tools (calculator, alarm, calendar, address book, still camera, and video recorder) that once required separate devices. For heavier-duty needs—spreadsheets, word processing, extensive Internet access, and other "traditional" tasks—settle on one "laptop/notebook" portable computing device.

Whether you choose to live in the Wintel or Mac universe, need a physical keyboard or a virtual one, want to compute in your device or in the cloud is a personal decision. How much weight you want to carry is personal too. But two devices should do it. Before you add another high-tech device to your carry-on bag, ask the obvious question: Can my laptop or smartphone do what the third device does? The answer is almost always yes.