We're a Suffolk family. Welcome.
Have season passes to BG every year, and have the calf muscles to show for it! Although WDW is so much bigger than BG, the walking is easier because there aren't many hills. (Except the hill to the monorail outside MK can be a killer at the end of a long day).
I've learned so many tips from these boards - I check in at least a couple of times a week.
There are so many musts at WDW - the classics like Haunted Mansion and Pirates of the Caribbean in MK, and the newer Dinosaurs and Himalayan rides in AK.
Go early as you can get into the parks in the morning, and fast pass the rides you want right away because the fast passes can go really fast.
Don't miss the MK fireworks at night.
There are so many great restaurants - read the dining threads to see what appeals to you. And definitely make advance reservations 180 days before your arrival - the reservations fill up, and it is hard to just walk in and get seated at the better places.
My personal favorite is Boma at the AKL, for both breakfast and dinner.
And for your first trip, stay onsite if at all possible. It adds to the magic.
NUNU 
