I'm on Pride of America August 8, 2004. I've never cruised Hawaii but I've been to the islands twice.
If you are coming from almost anywhere in the USA except the West coast I would suggest coming at least two days early. That time difference is huge and will have an impact on your body. You don't to spend the first days of your cruise adapting.
Also, I'm planning on renting a car for the time we're on Maui. Since you are there overnight, you will have a chance to really experience this island, and the only way to do so is by car. Its also probably cheaper than a tour.