for offsite budget minded (but still nice resorts) - I would recommend Cypress Pointe or Cypress Pointe Grand Villas. There is a back way (Turkey Lake Rd) to both Sea World (closest) & Universal.
But I definately agree with the other 2 posters, if it is in your budget, then I would stay onsite at Universal for front of the line access to all the rides all day.
Marriott Horizions is another (higher budget) suggestion for a resort near Sea World. I think the Peabody is also close to Sea World & your kids would get a kick out of watching the duck march daily.
I personally HATE International Dr - horrible traffic! That said, the Homewood Suites (runs about $170ish per night) is off International Dr but not the busy traffic part- it is basically directly across I4 from Universal - infact our room looked right out (well across) to the Hulk Roller Coaster. Homewood Suites is very nice, was extremely clean & has a sitting room with a tv, pull out sofa & a chair, kitchenette with stove top burners, nice sized refridgerator (not a mini fridge but slightly smaller than a house fridge). The bedroom completely closes off from the sitting room/kitchenette with french doors. It has 2 queen beds & an armoire with another tv + drawer space. The complimentary breakfast served in the lobby every morning has hot scrambled eggs, eggs with bits of ham, either sausage links or bacon (depending on which is served at the time you get to breakfast, the rotate out) also you can make your own waffles from batter they provide + juices, bagles, danish, fruit etc. Enough to fill up! Also Mon-Thurs they have a managers reception where they serve complimentary beer & wine. Highly recommend Homewood Suite (on Hospitality Way) if you want a hotel type atmosphere not onsite.