Hi Ashley! If you are planning on spending most of your time at the Magic Kingdom, I'd definitely recommend staying in one of the Deluxe hotels on the monorail line. That way you can keep the baby in the stroller right from the room to the park and vice versa. They'll be the closest to the Magic Kingdom as well. The Contemporary Resort would also be accessible by walking and you could keep her in the stroller that way too.
If you plan on going to Epcot or Disney's Hollywood Studios, staying at Disney's Beach Club, Yacht Club, or Boardwalk Resorts you can access both Epcot and the Studios by boat or walking. You can also then access the Magic Kingdom by the Epcot monorail, transferring at the Transportation and Ticket Center. Beach Club is one of my favorite resorts and really beautiful with, I think, the best pool area on property.
Each park also has an air-conditioned
Baby Care Center where you can pop in and feed, change, or let a little one nap quietly in her stroller or with you holding her. They are great to have in a pinch.
I hope this helps with your planning and your family has a wonderful vacation!
~Suzannah