Yes, and I have seen a few domestic widebodies on UA, too. Almost all of the widebody flights across all carriers are FL, HUB-HUB, or involve NYC, SFO, or LAX.
At ORD, I saw a few UA birds (744) heading SFO and LAX.
My parents also flew widebodies (767?) SLC-ATL and ATL-LAX as some of the legs on a trip last summer.