Hi Brandi,
I am very excited for your first Walt Disney World vacation! You will have so much fun. I would recommend looking at a one bedroom villa at Disney's Saratoga Springs Resort & Spa, Disney's Boardwalk Villas, or Bay Lake Tower at Disney's Contemporary Resort. I love all three of these resorts, and they each offer something special.
Since your children's birthdays are during this vacation, I would let the front desk know at check in as sometimes they can give balloons and a card signed by your child's favorite character. When you go to any of the theme parks, stop by Guest Relations and pick up a Happy Birthday button for your kids so other Cast Members and guests can help you to celebrate. At any Table Service restaurant, let them know about the birthdays, and your son and daughter can have a special dessert.
When you are not at the theme parks, you can spend time at the resort you are staying at. They will have children's activities available as well as playgrounds and pools. Downtown Disney is a wonderful place to go shopping and walk around as well. Miniature Golf is also a fun thing to do with your kids.
Kid's Nite Out is a babysitting service that is fantastic if you want a date night! They give one on one care in your resort room. There phone number is (407) 828-0920. Reservations can be made up to two months in advance and require at least a 24 hour notice.
Please send me a follow up question as I have so much more to tell you. Have a magical vacation!