I believe last minute plane swaps are a thing of the past on the Hawaii routes. If you are flying ex-DFW or ex-ORD to anywhere in Hawaii, you are going to get a lie flat seat in business.
For a period of time (2+ years ago), the angled lie-flat seat 763s were being swapped in for the fully lie flat ex-DFW.
In PHX, there was a chance you could get lucky and get a fully lie flat 757 swapped in for the old recliner seats on the HP-757 fleat. But those days are gone.
From LAX it has always been the A321-H with standard first class seats.
See discussion here:
Changes to Hawaii service since merger, late 2014 on (consolidated)