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: 100,399
As a Gold, I don't think you should realistically expect an upgrade, especially for a multinight stay.
If both locations are good for you, I'd pick lounge access and over a hundred pounds to spend elsewhere, so to me the Conrad would win.