1.Conventional wisdom is that you do one island in seven days. Packing and going to the airport/arriving/unpacking can take up more than half a day. If you are going for seven days, you have only 6 nights accomodation. One day flying in, one day flying out leaves only 4 free days. Don't waste one of them in another airport.
2. As I understand it, rental cars are not allowed on Superferry.
3. In early December, $175 a night would get a decent, but not perfect place. In later December, the Christmas holidays are going to really bring the prices up. And, remember there is an 11% state tax on accomodations. I checked on
Expedia.com - Upgrade your browser and see the world for Maui hotels the week of December 6, as an example. There are rooms, but you'd get a nicer place for $200 a night. For the week of Christmas, many of the big hotels are already sold out.
4. The price of meals will shock you, especially if you are dependent on your hotels for meals. A condo can save you money if you eat simple breakfasts and lunches, and maybe have a modest dinner out.
5. If it were me, I'd spend the entire time in Maui. I had a friend who just came back from Maui and really loved Lahaina shores condominium.
6. If you are on Maui, you will need a rental car. Don't wait too long to reserve the rate. Last December, there were no rentals available for the last week. And the last ones rented were unbelieveably expensive.
7.
Cheap Flights, Airline Tickets, Cheap Airfare & Discount Travel Deals - Kayak.com is great for comparing airfares/hotels/car rentals.
8.
..VRBOŽ is Vacation Rentals by OwnerŽ Vacation Homes Rentals by Owner can give you an idea about condo rentals.