Originally Posted by
RandomBaritone
Anything over 24 hours is a stopover, not a layover. You just need to use the UA website's multi-city routing tool. It's worked like a charm for me when I've priced out moderately complex itineraries like yours.
Alternatively, you could book two separate, nested round-trips, one SFO<>ORD and one ORD<>GRB. Might even be cheaper.
ORD-GRB round trip is costing me >$1035. Multi segment might work.