My DD was granted a wish this past fall. Her wish is to go to Hawaii as well. We asked for the wish to be in the summer so that our older 2 DD can go with (one just graduated from college and is teaching, the other is in college). We don't have any specifics yet but from what I understand, they will arrange everything. For us, that includes getting her special bath chair, special car seat and a case of diapers there. They are also taking care of arranging the plane as DD will either need a harness or an approved seat for the plane ride.
The only thing specific that she asked for was a luau. They suggested swimming with dolphins but because of her medical condition, we didn't think that would be a good idea. They said that if we don't have anything else specific, they would add extra money to the prepaid credit card so that we could use it as we saw fit. We are planning on going to Pearl Harbor as well but that is very inexpensive.
The last that I heard from our wish grantor is that they just got their allotment of air miles and are trying to book the flights.
We asked for it to be over the 4th of July as DD will be 16yo on July 3rd but we'll see. Either way, I'm sure it's going to be a great trip!
Best wishes to your family!