A FlyerTalk Posting Legend
Join Date: Sep 2009
Location: Minneapolis: DL DM charter 2.3MM
Programs: A3*Gold, SPG Plat, HyattDiamond, MarriottPP, LHW exAccess, ICI, Raffles Amb, NW PE MM, TWA Gold MM
Posts: 102,617
I'd probably pick DL for the empty middle seat, which makes coach much more comfortable.
AA Gold is like Silver with other airlines (25,000 miles first status level), so I wouldn't expect upgrades on a DC route (elite heavy) or really any other significant perks. I don't think AA Gold is an argument for flying AA, although if you're close to (re)qualifying for a (higher) status tier, it might be worth it.