Your trip is going to be very expensive. You're attempting to travel to Hawaii (a) during the most busy week of the year, when restaurants and activities have little incentive/need to discount, (b) during the peak of the economy and (c) making your reservations late. Unfortunately, the Holiday premium is going to be much higher than that of WDW. Here's my take:
AIR AND HOTEL - Until the Great Recession, the best deals on airfares came through consolidators; unfortunately, those fares are no longer available. Consolidators, OTOH, can save you significant money on rooms -- places like Pleasant Hawaiian Holidays, Funjet, Travel-Hawaii, etc. For example, for your dates, Hilton.com is showing ~$3600 as the lowest rate for your room (NOT including resort fee) at the Hilton Hawaiian Village (HHV) whereas one of the consolidators has it for ~$2900 (NOT including resort fees). Note that consolidated rates don't qualify for Best Rate Guarantee. For future reference, the earlier you begin looking (for Holiday travel), the better rate you'll get. A co-worker is traveling 12/24-1/1 (one more day than you), and in February, I helped him book a room at the HHV for $3200, including resort fee and breakfast buffet for two daily (which is $40 per adult, making it a $560 value).
TRANSPORTATION - It can take time to find a reasonable rental car rate in Hawaii, but try to decide if you need one. Parking at most high-end resorts is $40 and up, and $20 and up form most mid-tier properties. Finding parking at most attractions can be brutal, especially during the Holidays. Ride shares and busses may be a cheaper and better option; transportation from the airport to most hotels is generally inexpensive.
MEALS - The cost of food is slightly exaggerated on here. Stay away from hotel restaurants -- I mentioned that the Hilton charges $40 per adult for breakfast, but it also charges nearly $40 (including tip) for a large pizza. Plenty of lower-cost fast food, plenty of chain (Red Lobster, Outback, etc. for a minimal markup) and plenty of mom-and-pop shops with reasonable rates. Grocery store (Foodland, Safeway, etc.) circulars are online, which gives you an idea of cost (use common sense; e.g. stay away from Food Pantry in Downtown Waikiki and stockup elsewhere). One bonus is that Hawaii has tons of local produce that taste better than anything you can get on the mainland -- pineapple, bananas, onions, strawberries, corn, melons, etc. Paying $4 for a carton of strawberries that sell for 77c on the mainland sucks, but trust me, they do taste better. Invest in an entertainment book, Groupon, etc. to minimize resturant cost.
ACTIVITIES - Activities unfortunately aren't cheap. Expect to pay $100 per adult for a luau, $100 for parasailing, $150 for a dinner cruise, etc. During the Holidays, discounts are few. Best advice: plan everything out in advance.