MOST OF THEM!!!
Seriously Disney is set up for a proper family visit there is more than enough to do. Easier to say what is not suitable than to list what is. Make sure you catch the parades.
ones that won't be suitable in main park: Space Mountain, Indiana Jones but your little one won't be in the height limits for them anyway. One you should try (so my 4 year old went some of them but yours might not) Runaway mine train (less likely if he doesn't like rollarcoasters) Phantom manor, Pirates of the carribean, Space tours (ride simulator).
I have lots of must sees but for a four year old boy Buzz lightyears intergalactic spin is up there. If you have some time and want some quieter activities, try to spend some time exploring the walk round areas like the caves near pirates of the carribean, the dragons lair under the castle and Alices Labyrinth.
In the studios you won't get on crushes coaster, Armageddon, or terror of the towers. the rest is absolutely fine and there is lots to do. We don't tend to get to toyland so I can't comment on there. Backstage studio tour is fab. I would say it is entirely suitable but does involve stunts with fire and water.
Ratatouille (can't spell it) is incredible. Catch the Motor stunt show, it's awesome especially when Lightening Macqueen appears. However if you want to miss the burning man trick (not actually that scary) hide when the "hero" who is being chased by two motorbike gets/falls off his motorbike. Stitch live is truly special but means a lot more if you watch at least one of the Lilo and Stitch films before you go. Good for quiet time at the end of the day in the Studios is the back end of the Art of Animation Attraction (you don't have to go through the whole attraction to get to it if you don't want) just go through the back entrance by the art of Disney store.
The website has an interactive map that will highlight attractions. But they have messed with it and it appears to be totally naff atm 