Any ticket discounts for IOA? What attractions fun for 4 y.o.? First time visitors?
You can buy very slightly discounted tickets from Undercover Tourist, especially if you use the Mousesavers link for an extra small discount. Islands of Adventure has more of the intense rides, but the 4 year old would probably enjoy Dr. Seuss Land, maybe Spiderman, Dudley Do-Right and Jurassic Park (not sure of height restrictions), Also they would probably get a lot of enjoyment out of Harry Potter Land, even if they don’t know the story. The wand choosing at Ollivander’s would be pretty cool for them, and even better if they actually get chosen for the experience.
Undercover Tourist had the best prices. Their prices include tax which the Universal online tickets do not.
Suess Landing is awesome and is geared toward young children. However, they have two rides - Cat in the Hat(36 inches) and a train ride (40 inches) that may eliminate a four year old depending on height. Here is the height requirement link; Universal Orlando. There isn’t too much else in the park that is little kid friendly.
I think for first time visitors there is a lot to explore. I liked USF better but IOA is still a fun park.
Start by reading this page:
http://touringplans.com/universal-orlando/kids
Also, OrlandoTicketConnection is within a dollar or so of UndercoverTourist prices, and uses electronic delivery instead of mail.
http://www.orlandoticketconnection.com/product/universal-orlando-base-tickets/