Delta has been offering ‘economy comfort’ seating on its international aircraft, with additional legroom at the front of coach. It’s available for a premium but free for elites.

Wandering Aramean notes that Delta is now planning to roll out the extra legroom seating to all of their domestic aircraft, including two-cabin regional jets, by summer. Pricing will run $19 – $99 per segment.

However, they’re only going to be putting 3-5 rows of extra legroom seating in. So this is nowhere near as extensive as United’s offering, which will be extending to the Continental fleet over the coming year as well. United’s new configuration 777 — which has 9 seats across in coach — offers 12 rows with extra legroom.

Delta’s economy plus seating will be available for free at booking to their Gold elites and higher (internationally, they restrict this to Platinum and Diamond members). These seats will also be available for free at booking to customers purchasing full fare tickets. Silver elites will be able to purchase it at booking at 50% off or assign remaining available seats for free at check-in.

United used to offer complimentary economy plus to full fare passengers, and then removed the benefit which never made sense to me. When United was operating one-class TED aircraft on routes like Washington Dulles – Las Vegas, that meant a non-status passenger buying full fare first class London – Washington Dulles – Las Vegas would be required to “buy up” to have additional legroom in coach for the DC-Las Vegas legs. At least Delta ‘gets this’ and offers full fare ticket purchasers a reason to choose Delta over other airlines by throwing in extra legroom seats which they might not get on a competitor.

United recently announced that for 2012 they’d be denying their first-tier elites economy plus seats at booking, offering it for free only at check-in. And Delta is following United’s lead here in not offering the extra legroom seats to their Silvers. (Of course United isn’t discounting bottom-tier elite purchases of these seats as Delta will be doing.)

With Delta’s extra legroom seats available to Gold elites and higher for free, I really don’t expect too many silvers to be able to secure these premium seats for free at checkin — unless they hit the seatmap just as Delta processes upgrades for folks who had previously been assigned these seats.