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: 100,404
IME the cheaper DL fares that I've seem require outbound TPAC segments Monday through Thursday, so your days should be fine, although I've mostly looked at the D1 Z fares. You need to connect through a third country such as Japan in one direction for TWOV (and you cannot visit both PVG and PEK on the same pass through China).
If you travel in November or later, the DTW flights should use the new A350s. Check the DL forum for updated details on the dates they're scheduled to be introduced on these routes.