I fly Hawaiian Airlines from JFK to Kona about every other month. I will buy an economy fare and use miles or an upgrade certificate to upgrade. I am flexible when I fly so I can track the availability of mileage upgrade seats before I book. As a caveat I try to fly only HA as I have to change at least once to get to Kona. IF not HA both flightsthe other airline could be JetBlue. I don't know how the mileage upgrade or seat selection works with JB as it adds a layer of complication that I don't want to deal with. These days a miles only FC ticket takes a lot of miles each wayif available. You can find a lot of the details of the mileage requirements in the Pualani rules at the HA website.
You don't indicate if where you are flying from and to (assuming there is more than one stop and if interisland flights are involved). Nor do you indicate if you are a member of the HA mileage program and which status (Gold or Platinum). Also when you want to book the flights matters (high demand- school vacations/holidaysany flexibility of the days coming or going). Each of these factors could make a difference to how easy it is to upgrade.
I wouldn't count on using points for upgrades unless everything aligns. Mileage upgrades require 25,000 or 50,000 each way and based on availability. The 160,000 miles you mention wouldn't be enough for all 4 of you both ways. I look at Expertflyer website (maybe there are other websites) to see how many 25,000 or 50,000 seats are available on a particular flight/day. During covid 25,000 was possible even from JFK. This past year with the demand up mostly I see only a few 50,000 miles upgrades or none at all for the JFK/HNL flight. There are only 18 FC seats on the 330 model airplane and the seats allocated to upgrades and mileage are limited. Once in a while I will fly to Kona from the west coast and for those flights I might see some 25,000 mile upgrade seats. Depends on the origination airport.
Note that the availability for upgrade can change any time as people cancel or change flights. You can call Hawaiian Airlines to ask if there are any upgradesbutI find it faster to look at Experflyer and not wait for customer service to ask.
If you have a return flight which is a red eye you might consider saving the miles to try to upgrade for that flightespecially if there are FC lie down seats. Otherwise you can pay to upgrade to a "comfort seat" which is a bit larger and mostly found in the front of the plane. On the 330 there are two rows of those "comfort" seats right behind FC and quite private. You can look at a seat map for the 330 and see. You cannot use miles to upgrade to the comfort seats. Butif you are a Pualani member you maybe able to upgrade for free before the flight. Butyou don't know that till basically the last minute before you fly. HA also may offer a paid upgrade when you check in (cost affected by Pualani status) or a bid up to first class offer. I have heard that the you must bid up enough to have your offer accepted and that they may leave FC seats empty rather than fill them for a low bid. I've never bid up so I'm not sure about that or if it is true.
