In an effort to provide better service (and generate ancillary revenue), airlines have been introducing a swankier version of coach seating for a nominal fee.

When travel budgets can’t accommodate the astronomical business class ticket prices, travelers can still enjoy some of the amenities like priority boarding - handy for ensuring space in the overhead bin - and more leg room. Elite-level frequent fliers benefit the most - those at the highest levels are often granted advance complimentary access to the seats.

Here’s a roundup of the latest premium coach offerings on some U.S.-based airlines.

AMERICAN

The most recent airline to offer affordable premium economy seating, American plans to roll out the new configuration to its entire fleet within 18 months. Travelers will be able to purchase “Main Cabin Extra” tickets later this spring for summer 2012 flights. The cost will be an additional $8 to $108 per flight segment depending on length of the flight, and that will buy you an additional four to six inches of legroom.

DELTA (DAL)

Delta introduced “Economy Comfort” on long haul international flights last summer, and is rolling it out to 800 more aircraft. As with American, you can purchase this fare class in late spring for summer 2012 travel. For an introductory fee ranging from $19 to $99, you’ll get a seat pitch of at least 34 inches (compared to the standard 31). Highest-level frequent fliers get free access, those in lower tiers can purchase the seats at a 50% discount.

FRONTIER

Frontier offers “STRETCH seating” in the front rows (5 more inches of legroom, up to 36 inch seat pitch) and exit rows (7 more inches of legroom, up to 38 inch seat pitch) of some of its planes.  There’s a slightly complicated system to determine whether you’re eligible to purchase the upgrade based on route and fare option, but elite level travelers will get free upgrades and the rest can purchase access starting at $5 to $15 a flight segment.

JETBLUE (JBLU)

JetBlue’s “Even More Space” seats boast a 38 inch seat pitch, impressive for a U.S. airline. It costs between $10 to $65 more per flight depending on the route, but for now it includes free access to “Even More Speed”, the airline’s expedited security option.

UNITED (UAL)

Their long-standing “Economy Plus” seating was introduced in 1999, but they’re still in the process of retrofitting Continental’s fleet. For now, the upgraded seats are available on long-haul international flights from New York and Washington to European destinations. Gold-level fliers get advance free upgrades from Economy, and silver-level members are offered the upgrade if available upon check-in.

As you can see, not all premium economy seats are equal in terms of cost and what you get for the money. Do the research before you upgrade: Seat Guru makes it easy with their handy Premium Economy Comparison Chart detailing U.S. and international airline offerings including seat width, seat pitch, laptop power, power type, video and Wi-Fi availability.