Those will probably be two of the busiest days of the entire year at Disney unfortunately.

A PP referred to the iPhone app. It is definitely worth doing because you can get real-time status on ride lines. This lets you change up your plans to avoid long lines. I used mine constantly.

don't go, save your money- I am only half kidding. Am I the only one that feels Disney is overrated? Feel the same about their cruises

I just booked our christmas vacations through Pixie Vacations. Amy gave us personalized itineraries that told us crowd levels and daily park recommendations. Best of all there was a discount that saved us $800! I found her at www.pixieamy.com

We were at Disney during a Monday on spring break and didn't get there until noon. Honestly the lines were not so bad, the worst was the line at WDW to get on the ferry coming home, after the fireworks show. The monorail was even worse, best seemed to be the resort boats.
Have fun and I recommend booking a character lunch or dinner in advance, somewhere to get out of the chill, take a rest and have a decent meal.