Business class too pricey? Coach class too dicey? Then consider something in-between — a rapidly expanding “fourth class” of airline seating commonly called “premium economy”. These seats are a step up from coach in terms of comfort and price, but several steps below business class.

Many companies with bans on business class travel have embraced premium economy as a way to offer employees a bit more space and comfort to rest or work without breaking the budget. Premium economy also offers individual travellers a way to pay slightly more to escape the stress and discomfort of standard coach.

By 1 June, Delta Air Lines will have completed a rollout of what it calls the "economy comfort" section on its long-haul international fleet. Passengers in the new section get a standard coach class seat that offers 50% more recline plus four additional inches of legroom and complimentary cocktails. Most will have in-seat power plugs and free HBO. To get one of these seats, coach passengers pay an additional $80 to $160 each way when booking their seats; elite level members of Delta's SkyMiles program get the seats at a discount or free.

Delta's move follows United's recent decision to expand its popular "economy plus" seating to Continental aircraft (starting in 2012) due to the merger of the two carriers. Economy plus seats are standard coach class seats near the front of the coach cabin with three to five extra inches of legroom. Unlike Delta's product, United's economy plus option is on both domestic and international fleets. All elite level members of United's Mileage Plus have complimentary access to the seats; others pay as little as $9 for short hops, or as much as $100 for transoceanic flights.

Low-cost US carriers Virgin America and JetBlue also offer upgraded economy class options. Virgin's "main cabin select" seats are standard coach seats located at bulkheads and exit rows. Passengers get more legroom, complimentary food and beverages, and reserved overhead bin space. JetBlue's "even more legroom" coach seats offer four extra inches of legroom. Both carriers charge extra for these seats based on flight length.

Tip: If seats are not sold by the day of departure, many airlines will frequently offer last minute discounts off the standard premium, so be sure to inquire when you check in.

The concept of premium economy is more upscale and exclusive on non-US airlines. Offerings vary among carriers, but typically, non-US premium economy seats are slightly wider than standard coach seats, offer more legroom (some offer leg rests), have larger in-seat video screens and are located in a separate cabin. Food and entertainment options are closer to what passengers get in business class. Some offer power ports for laptops or other devices. And they typically cost about 65% less than business class seats according to, a website that helps passengers choose airline seats.

Some non-US airlines have embraced the concept, while others have ignored it. For example, in Europe, British Airways, Air France and Virgin Atlantic offer premium economy on nearly all long haul international flights, but Lufthansa does not offer it at all. KLM's product is similar to that of Delta's "economy comfort" in the US.

In Japan, both ANA and JAL offer premium economy. In Oceania, you'll find it on nearly every carrier operating long haul flights, including Qantas, Virgin Australia and Air New Zealand (which offers a radical and popular new "space seat" design on its Auckland-Los Angeles-London run).

How much do these upgrades cost? In most cases, it depends. To reserve one ahead of time on a popular flight you'll pay the full premium. But if loads are light, asking at the last minute could yield a bargain.

Chris McGinnis is the business travel columnist for BBC Travel.