Hello fellow parent of twins!
If you're looking at the deluxe resorts, then in my mind the decision becomes ... Do I go to the Yacht/Beach Club for the pool and the proximity to Epcot/DHS? Or, do I go to the Grand Floridian/Polynesian for the monorail access to the Magic Kingdom (I'd stay away from the Contemporary because of construction, but that's just me). You can see my answer to a similar question
here.
To decide, I would actually go at this a bit backwards. Look at some guidebooks, the WDW website, and the website allearsnet.com. Map out your touring and dining priorities. If the vast majority of your touring and dining will be in the Magic Kingdom area, then I'd do the Floridian or Polynesian. The choice here is just which themeing do you prefer, tropical or casual elegant. If your touring will be spread out evenly to all the parks and you'll be doing evening dining at Epcot/DHS/Boardwalk, then I'd choose the Yacht or Beach Club.
You really can't go wrong with any of these hotels. They all offer first class accommodations and are all great places for kids.
Hope you have a great trip!