I'm not exactly sure where the cheapest east coast or midwest destination would be, but if your end destination is Denver this might work:
Find somewhere on the east coast or midwest with a $200ish rounnd trip fare from SFO. Book SFO-ORD-XXX-ORD-DEN-STOPOVER-SFO so you'll get the 3200 miles in the trip ending in Denver. Since DEN is a $55 stovover fee on any trip that involves a legal connection in Denver, this would be perfectly legal and you could just throw the end of the ticket away (or book it for another time).
I played around and found MKE for $509; I'm sure you could do better. Routing is SFO-ORD-MKE-ORD-DEN for 2400 EQMS.
United Airlines Flight UA134 on a Boeing 767 (jet) in coach class
Departs San Francisco, CA (SFO) Sat, Nov 10 8:50a Arrives Chicago, IL (ORD) 3:01p
United Airlines Flight UA6062 on a Canadair Reg. Jet (jet) in coach class (operated by UNITED EXPRESS/SKYWEST)
Departs Chicago, IL (ORD) Sat, Nov 10 4:05p 44 min
Arrives Milwaukee, WI (MKE) 4:49p
Milwaukee, WI to Chicago, IL: 66 miles 53 min
United Airlines Flight UA5891 on a Canadair Reg. Jet (jet) in coach class
(operated by UNITED EXPRESS/SKYWEST)
Departs Milwaukee, WI (MKE) Sat, Nov 10 6:16p 53 min
Arrives Chicago, IL (ORD) 7:09p
United Airlines United Airlines Flight UA959 on a Boeing 737 (jet) in coach class
Departs Chicago, IL (ORD) Sat, Nov 10 7:50p 2 hrs 38 min
Arrives Denver, CO (DEN) 9:28p