Late Night Service on Friday and Saturday Night and on Holidays.
There should be even two runs, on at 130am and another at 230am after last call on Friday and Saturday nights in addition to 4th of July, New Year's Eve, Halloween, Cinco de Mayo, SF Pride and other similar events.
If funding is the issue cut and paste the lowest ridden trip during the day and the last trip of the day. And only do it on Light Rail and the major cross county lines such as the 23, 24, and 66/68.
It will save lives from drunk driving accidents and increase tax revenue from more people going out.
At the very least have it occur every other week on a Friday or Saturday night just on light rail.