When visiting Maui an earlier morning is definitely worth it even if you are on vacation. The drive to the top of Haleakala can be a long one especially if you are on the western side of Maui. However when you get to the top and experience the cool temperatures and in most instances the sun rising over the clouds you will know you have made the right choice. You can always head to the beach or pool and take a nap when you get back to where you are staying.
One suggestion I have is to make the trek early in your visit, as the time zones will be working with you for when the alarm clock goes off in the middle of the night.
Prints: Above the Clouds in Hawaii