I just booked a trip on Alaska - - San Diego to Kahului non-stop and then Kona to San Diego non-stop.
Originally I was going to fly both into and out of Maui but I was having trouble finding a non-stop flight that I could upgrade to first class with miles. I learned a lesson that (it appears) Saturday flights on Alaska are less likely to be degradable than, say, Wednesday or Friday flights. So I moved the arrival date up one day and got an upgradeable flight to Maui. But we were still having problems getting upgraded on the return flight.
On the return trip I decided to fly directly out of Kona (to San Diego) and was pleased that the flight was upgradable. I noticed that there were LOTS of available seats on this flight. I'm hoping that they have enough people flying that they don't cancel this flight.
"All in", I think that I have invested around $1100 and some miles to get two round-trip non-stop first-class air tickets.
(If I would have flown in and out on a Wednesday, I probably could have saved $300-400.)
I'm thinking that if people are really interested in getting a mileage upgrade and are otherwise having trouble doing so, that flying from San Diego into Kona might not be all that dumb of an idea - - it only costs about $100 one-way to go to the other islands.
Like Artringwald and others, I booked using the $99 Companion fare and then upgraded to first class at a rate of 15K miles per person per leg. Not all that bad. (Thanks Art for your advice on this subject in the past).