Chris Elliott offers some advice on when to save money on travel and when not to. He gets more right than wrong, but his piece needs a few corrections.

Elliott is on the money that: a good travel agent is worth paying for, it’s worth spending miles to upgrade to business class on (most) international trips, and that the Hilton Garden Inn is generally a good business hotel. Bear in mind that similar brands may not be as consistent — Four Points by Sheraton has some good properties (Los Angeles airport and Sydney’s Darling Harbor locations, for instance) but also some real dogs. While my own travel preferences tend more towards a W or at least a Westin, mid-price business hotels remains sound advice.

Elliott properly cautions that paying a travel agent is overkill on simple recurring trips.

He might have mentioned that some airlines are easier to upgrade with (such as American on the easiest end of the spectrum, followed probably by United, and then Delta and Continental as most difficult).

And I agree that it’s rarely worth picking an off-brand rental car company whose location is off airport. Hertz and Avis offer #1 Gold and Preferred service, respectively, that makes paperwork and getting out of the airport far easier. (I find that Thrifty, which does offer “Blue Chip” service, is more often off-airport and still requires going to a rental counter to process paperwork. Big negative in my book.)

The one area where I think Elliott’s piece needs qualification and explanation is his advice to

Book a ticket on an airline with a one-class configuration. That’s right — try Southwest, Song, Ted, or one of the other low-fare airlines. There’s a fierce battle for customers among these no-frills airlines at the moment. In fact, it isn’t really fair to call them “no frills,” because they offer first-class amenities for the price of economy class. Your productivity won’t suffer because there’s usually plenty of legroom in these one-class cabins, as opposed to two- and three-class configurations, where everyone in the back suffers in “cattle class.”

First, not all one-class carriers are created equal. And not all seats aboard those carriers are created equal, either.

JetBlue does offer more legroom, but only behind row 10 due to the placement of the emergency exit row.

Ted offers extra legroom, but only ahead of row 13 — and the premium rows are open only to elite level flyers and (close to) full fare passengers, except at the airport where a passenger might be able to get lucky mooching the better seat.

Southwest hardly offers first class amenities. While not a one-class carrier, and so not specifically recommended in the column, Airtran’s coach class has less legroom by an inch than its major airline competitors.

The extra legroom claim is uniformly true for Delta’s Song and virtually true for an airline he didn’t mention — Frontier. All of their Airbus aircraft offer 33 inches of pitch. Only their Boeing 737s offer the standard 31.

Finally, when selecting a low cost carrier, it’s important to know what your backup options are. In the event of a flight cancellation, does the airline have an alternative way to get you to your destination? Do they have an agreement that allows another carrier to accept your ticket? Do they have earlier flights for you to switch to if you finish your business early?

Low cost carriers can certainly make sense. For the non-elite flyer JetBlue’s transcon flights may be a good idea, for instance. But it isn’t always a no-brainer — especially when major carriers generally match their competitors fares, at least for similar flight times.