I too am flying HNL-PPT at the end of August and had the same questions.

Here's what I found out when calling HA:

Our tix were $750 each for HNL-PPT on 8/22 and back on 8/26. That was the cheapest coach fare available. The cost to upgrade in advance is about $650 additional per ticket. No way.

So, since the return flight is a red-eye(12:05am!), I cashed in 30,000 HA points for 2 one way upgrades. At least be able to relax a bit better on that leg.

I've never flown HA, but I signed up for an account, got about 1500 points in bonuses(500 for customizing a PIN and 1000 for the ticket jacket game), transferred 14,000 AMEX points in, and then bought the remaining 14,500 points for $.025/mile = $362.50).

More info on purchasing miles is here:

http://hawaiianair.com/hawaiianmiles...m/purchase.asp

Or Call them for more info:
1-877-HA-MILES