Thanks to recommendations from this board, I tried Dim Sum King in Daly City/Skyline one late night last week.
Food was good and, perhaps more importantly, very fresh. (AT DSK, dim sum is ordered off a menu; it doesn't circulate on carts or trays.) However, it's no longer open 24 hours. It closes at 10 p.m. on weekdays and 11 p.m. on weekends.
That having been said, I think it's still the best option for those craving late-night dim sum on the way to or from SFO.
Thanks for the tip, all, and hope this update helps others.