Because of the age of your dds, I would recommend that you look into a resort close enough to get back to the hotel for nap times in the middle of the day. A monorail resort would be very easy for you, and I suspect you will spend alot of time at the Magic Kingdom, anyway. If you're not doing the naps, then I guess it isn't as important. The Swan & Dolphin have a launch to Epcot, so you could commute easily that way, as well. AKL is kind of off on it's own, but you would have dedicated buses, and a kids' club, if you're looking for a night out.
I recommend you go to allearsnet.com and look at pictures of the resorts as well. Get a sense of what they have to offer, and the distance to the parks where you will spend most of your time. Also, do you want character dining on site? A food court? table service? At the age of your girls, I would be more into the amenities I needed. They will feel the Disney magic wherever you stay!