I have faced the exact dilemma as you describe above with my own children and come up with an unorthodox solution.
First with capacity controls, it will probably be difficult to find four seats on the same plane using miles, even if you book 11 months in advance. Second, the use of 40K miles for a five hour flight to Hawaii is a bit wasteful, especially if you might use them at a later date to fly internationally in First or Business Class.
As you may know, Alaska Airlines has nonstops from both SJC and OAK to both LIH and OGG. Their physical ammenities on Alaska may be a shade lower than American or United, but the high quality of the flight attendants more than make up for the difference.
Right now, the OW fares on these routes are about $650 OW per person.
Using the Alaska Airlines Bank of America visa you will receive a companion ticket for $99, which can be applied to the first class fare. There seems to be no limit on how many cards you can get as long as you pay the $75 annual fee.
https://www.applyonlinenow.com/USCCa...03888-713717#b
YOu can get one in your name, one in your husband's name, or a business name and yield two companion certs.
Using this approach, your costs would be:
Two application fees x 75 = 150
RT in First for two people OW 650 x 2 = 1300 per person or $2600 for two.
Companion fare (99) x 2 =200
Misc taxes = $50
Total = $3000
Now, lets examine the miles that you get in return:
320,000 miles saved on United or American, which could be used for several business class tickets to Europe, Asia or Africa.
Signup bonus for the alaska credit card: 25000 x 2 = 50000 Alaska miles
Miles earned on the flight, which can be credited to the Alaska or American FF programs, including miles for the companion fare 5000 flt miles x 1.5 FC multiplier = 7500 x 4 = 30,000
In summary, by using this strategy, you spend $3000, and get in return:
The flights, including our people in the same cabin (no capacity controls as these are full F tickets), and the ability to change dates without penalty.
About 400K miles.
If you have the funds and would value the miles for use at another time, this strategy should work very well. You could use your American miles one way and this strategy on the return as well.