Supply, meet demand.
OGG has very limited lie-flat options compared to HNL as I'm sure you know. If you don't mind the extra 90 minutes or so could always try routing through there.
The other thing killing you is your quantity. A single first seat on HA a330 mid sept was $1,100ish but shot up once going to quantity 4. United can get you all there lie-flat for closer to $1,000. But you'll need to look closely at the seats - it's a big difference between polaris and the old 2-4-2 embarrassment that is now returning as the 777-200 craft are rotating back in. Although with 4 of you, maybe the 2-4-2 isn't as big a deal.