I would plan on two days-then you will have time to ride and also time to eat at the great restaurants.
I think the food at US/IOA is much better than at Disney and the prices are better also. My favorites are Margaritaville, Nascar Cafe and Bubba Gumps. However, I have not visited many of the restaurants and have heard great things about Mythos. Other places I want to try are Finnegans and Louies.
If you are visiting during high season then you can get Front of the line access(FOTL). You will have to pay for it or stay onsite to get it. If it is not a super busy time then I would not worry about lines-they are usually very reasonable. In Feb. I would not get FOTL as lines are not usually an issue then.
There are many rides your kids(and you) will love. For the roller coaster fan there is Hulk, Dueling Dragons, Rip Ride Rocket, and Mummy. I would not miss Spiderman, Simpsons, MIB, Jurrasic park river ride. You really should be able to get everything you want done.