For example, I found seats departing Cleveland CLE on Tuesday, July 3, returning from San Francisco SFO on Friday, July 6.
Other dates are available the first week of July and from late August through mid-February, excluding peak winter holiday travel. This fare also works from San Francisco to Cleveland, but only for fall/winter travel.
This is a basic economy fare, which means only a small personal item is included and you won't be able to choose a specific seat. Checked bags are $25 each way. Alternatively, purchase the $188 roundtrip main cabin fare if you want to avoid basic economy. The main cabin fare will include a carry-on bag plus personal item and standard seat selection.
Need a room in San Francisco? Here is what is available for the above dates on Hotelwatchdog.