I still remember a very long, relaxing dinner at Narcoossees. My baby was 2(he's now 14), he slept through the entire 2 hr dinner in his stroller, never even stirred.
When our young children slept this past week, we just walked around and enjoyed the theming. There's so much that you don't notice when you're rushing from ride to ride.
Our number one tip for getting an infant to sleep in the MK...go on the Haunted Mansion. I don't know if it was a defense mechanism or what, but all my kids alway fell asleep during this ride!
OR the ride gets stuck in the popping head room and your child screams bloody murder because this woke them up - yup, happened to me, so I would strongly not encourage this. The ride is loud.