I have never stayed at a value, but I wish we did for at least our first trip. The resorts look very Disney-esque, and like previous posters have said, save the $$ for something else at the world- maybe BBB?
We stayed at POR for our first onsite stay, then AKL, next will be BC. The POR rooms seemed really small for our family of 3, but we had just spent 5 days at a one BR condo before moving to POR, so that makes sense. I think, for us anyway, it would be hard to go backwards in room size and amenities now, and we now have missed that experience in our lives.
I say do a value first and save the $$$. Besides, as the girls grow older, they will need more room, and you will prob move to the mods or deluxes, so savor the experience of the values for now.
As another poster has said, you prob will spend most of your time outside the room for their first trip anyway, so why pay for more than you will use?
JMHO