UA: CVG to SAN $268 RT 5.79 cpm
Valid dates that I've found are every Tuesday and Wednesday from March 14th till the end of April. Other dates include May 2, 6, 8.
$268 for same day arrival and departure.
4634 total miles for the trip. CVG-ORD-SAN-IAD-CVG.
Hope this finds some value to some