AA ORD-DUB is with a two class 767-300, so business class on that route, as it has no first class, is pretty nice. You'll get the "almost flat" new generation business class seat, as well as a personal entertainment unit (looks like a laptop), and a double wide tray. You'll find a listing of sample programming HERE. You may want to select a center aisle seat to avoid blocking someone in for the flight across the Atlantic.

Be careful of certain One World partners. If you fly BA from the U.S., you cannot accrue AA miles (workaround: travel via Canada), so that flight could not be used towards a challenge, and you could end up with no miles. There might be one exception to Manchester IIRC.

AA runs MD83's later in the day from SEA-ORD which don't have any entertainment at all (also 2 class planes), though they will have powerports if you bring a laptop along (75 watts, cigarette plug style adapter), so don't get too excited about those. They're the workhorse of the AA fleet.

If you're looking at building miles for upgrades to Europe, are you aware of the copays to do that?