I have heard fairy tales of people getting reception on a plane with the antenna headphones and sitting next to a window but I haven't done it myself so I am not sure. Also, I am not sure how the FAA looks at satellite radio devices. If I were you I would just record some of your favorite radio content and roll with it on the plane.
As for Hawaii I have heard a few complaints that it is difficult to get a signal there. I would find out if the hotel you are staying at has wifi and hook it up that way. That will probably be your best bet.