I signed up and used Expert Flyer to check the "population" in various flight paths between HNL and GRU. If I could I wanted to schedule a few days in SFO on the way back, but I didn't want to pay a premium. EF showed NO Z's anywhere, but...
called Deltas Premium Sales line, and I got a really good one this time. He found Z's all over the place, coming and going, and found K's between HNL and SFO so I could use my SWU's to max benefit. I paid for an M between SFO and GRU return, and got my layover at minimum hassle, I'll jump down to LA early a.m and catch the LAX/HNL for a midday arrival. This is the ideal for me, I live Hilo and all the SFO's land after the last interisland. All in all, the preferred dates were available, and there were bracketed days with upgrades as well.

I know M's are more expensive now, but.. plenty of upgrades for the Intl. leg and, what surprised me the most, the continental runs were all easily upgradeable as well.
I burned 3 SWU's, 5 to go.