SF, UA959,

You are both pretty close - I can find a $574 'W' class fare SFO-HNL in the right date range.

However, what is odd is that if I leave Friday 10/22 and return 10/24 vs. Thursday 10/21 return 10/24, the ticket price goes up about 500 bucks.

Apparently there is a special fare category now requiring 3 night stays

Same return flight, seemingly same outbound availability both days.