The DTW clubs at the North or South Tram stations - on a quiet, midweek evening, as the sun is starting set on the horizon, grab a drink & snack and a quiet seat by the windows and watching the aircraft movements outside.
The ORD club is pretty nice, again when its quiet.
While the former NW clubs in my opinion still the nicest in the system, of the former DL clubs my pick goes to CVG or BNA.