So you're in New York, and you need to get to Milwaukee. Your search reveals there are two nonstop services for about the same price. Both of them are out of LaGuardia. AirTran can do it for $202 round-trip; Midwest Airlines can do it for $214.

You might never have flown on either airline, so you do what most people would do. You go for the cheapest seat. Or do you? Don't you want to find out the seating arrangement?

Airlines will tell you that you should never count on a specific plane before actually seeing it at your gate. This can be true. I still remember a particularly grim flight on a circa-1980's Delta 757, after having booked a ticket on the short-lived and superb Song Airlines (Delta’s brand within a brand with its seat back entertainment and leather seats.)  Instead, the airline substituted a non-Song mainline Delta 757 with none of those amenities.

Caveats aside, you can generally expect to fly on the plane you were told you'd be flying on at time of booking. A quick search on many booking sites would inform you that   AirTran flies Boeing 737 both ways from New York to Milwaukee. For Midwest, it's a Boeing 717 both ways.

Starting at airtran.com, I try to learn a little more about the interior of the 737. While I learn that there's free XM Satellite Radio and "ergonomically correct RECARO brand" seating," I know nothing about the kind of space I'm going to have.

This calls for a visit to Seat Guru. Here, I learn the shocking truth: AirTran seats have a scant 31-inch pitch -- considered one of the worst in the world of domestic economy class.

A quick explanation of pitch, or seat pitch: It's defined as the distance between a specific point on one seat (say, yours) and the seat in front of you (say, that guy whose bald spot is practically in your face) or the seat behind you (the one belonging to that guy tapping on his laptop so hard that the movement of his seat tray is making you feel like you're in the middle of a small earthquake.) 

So, AirTran coach seats: rather cramped. What about Midwest? They are flying a 717. On midwestairlines.com, I discover that their 717's offer 2-2 seating (as opposed to the usual 2-3 or 3-3 you find in domestic economy cabins, generally.

Seat Guru's information page on the airline's 717's reveals that while there is just a 32" seat pitch, seat width -- a dimension people tend to talk less about, but one that is important when considering breathing room on a plane -- is a whopping 21 inches. Compare that to AirTran's fairly standard 18.

So for virtually no price difference at all, you get more space on Midwest.

For now, anyway. Spokesman Michael Brophy says that Midwest will be converting its 717's to offer two styles of seating. Forty "Signature" seats (at extra cost) will remain 2x2 and offer better seat pitch – 36 inches -- while 59 "Saver" seats will go 3x2, retaining the 32-inch pitch.

This brings the 717's in line with the company's MD80's, which already have a similar layout (with less Signature seating, however.) Signature seating will cost $65 more than Saver seating, per segment. Some things won't change, however: Nice leather seating, proper in-flight meals for purchase, and, best of all, free, warm chocolate chip cookies. 

JetBlue offers most legroom

Midwest was always a special airline -- but it has had to finally learn the hard truth that other airlines finally faced. More room is appreciated, but customer appreciation doesn't always pay the bills. Just ask TWA -- if they were around to ask anymore. Converting coach to the more roomy Comfort Class made waves and won awards in the early 1990's. By 1994, it had been canned. The airline was acquired by American in 2001. (At the time, American was offering a similar service, called "More Room in Coach," which offered seat pitch of 33-34 inches throughout most of their economy cabins. That scheme went the way of TWA by 2004.

United never depended on anyone's goodwill in its Economy Plus scheme, which features a few rows of more spacious seating -- on an Airbus 320, for instance, you'd get a nice 36" seat pitch -- if no more width than the rest of the cabin (18" -- again, fairly normal). You will also pay for this. Prices depend on length of flight, according to the airline. A short hop from their Denver hub would run you $14, while a Denver-Honolulu flight would cost $61 each way. Formerly offered as a complimentary service for its most elite mileage members, the rules have been loosening over time. Spokesperson Jeff Kovick says that all customers may purchase EP seats "at the time of booking or on the day of check-in, pending availability."

JetBlue appears to have taken a page from United's playbook. When it removed seats in the front of the cabin to give rows 2-5 on its Airbus A320's a whopping 38" seat pitch, it began charging $10 for short flights, $20 transcontinental and other long flights. But you don't have to upgrade to get ahead – even the regular seats on JetBlue offer an industry-leading  34-inch seat pitch. That is even better than Frontier, known for its fairly friendly 33-inch pitch on its A319 planes.

Best and worst planes

So which airlines and specific aircraft within those airlines have the most and least seat pitch?

We consulted Seat Guru’s handy comparison charts  for some answers. Excluding United’s Economy Plus seating, here are the top choices:
1. WestJet Boeing 737-800’s 34 inches
2. Air Canada Embraer ERJ-190’s: 34 inches
3. Air Canada CRJ-705’s 34 inches
4. JetBlue Airbus 320’s: 34 inches (38 inches if you pay extra)
5. Frontier Airlines Airbus 318’s and 319’s: 33 inches
6. American Airlines 767’s: 33-34 inches
7. Southwest Airlines 737’s: 32-33 inches

Which have the most cramped seating? Some of the worst are:

1. Northwest Airlines DC9-30: 30 inches
2. US Airways Boeing 737-400’s and Airbus A319’s and A320’s: 30 inches
3. Airtran 717’s: 30 inches
4. USA3000 Airbus A320’s: 30 inches

In fact, the vast majority of commercial jetliners have 31 inches of pitch, with an additional handful offering 32.

If it’s seat width you’re looking for, stick with the aforementioned Midwest Airlines 717’s, and Virgin America’s Airbuses (19.7 inches). Most other planes have 17-18 inches, according to SeatGuru.

On planes flying international  routes, you’ll find similar disparities between airlines. Most carriers will only give you between 30 and 31 inches of seat pitch, even on long haul flights (no wonder we all arrive in such bad shape). Among the airlines affording those all important extra inches (all at 32) are Air Canada, Air France, Cathay Pacific, Thai Airways, and Virgin Atlantic. But if you really want to sit comfortably, Air New Zealand’s 747-400’s, Asiana’s 747-400’s and Emirates’ 777’s offer a whopping 34 inches.