Monica,
For me, the dad of two girls (now 4 and 6), the theme of the resort is very important. I like to help make our resort the "fifth park" for them, playing to the theme. We really got into the luau/Hawaiian thing when we were at the Polynesian, for example.
So here is where I would go, based on your girls, by resort category;
Deluxe: Grand Floridian
This is the most princess-y of the Deluxe resorts. And at their ages the monorail access to the Magic Kingdom is a huge plus.
Moderate: Port Orleans Riverside
Yes, I think that the Princess themed rooms look like an over-the-top good time for two little princesses! But even if you did not get one of these rooms, I still think this is the best choice in the Moderate category for you. It is wonderfully themed, quite whimsical, and the most feature-rich of these resorts.
Value: Art of Animation
Obviously I have not been there yet, but if they are open for you I think that the Little Mermaid rooms might be quite special.
I hope that this helps? Write me back if you have any follow-up questions by going to my bio page!
Have a magical vacation!