Dumbo!
We arrived about 3PM on a Wednesday - and were immediately offered a ride on one of the antique cars up Main Street (as we didn't have a clue where to go or what to do) and were dropped off at the hub.
We walked through the castle into Fantasyland, asked the kids what they wanted to do first, and years and years of seeing that ride on TV made its mark and they insisted on Dumbo.
It was one of the few rides we ever queued for, and, truth be told, one of the least interesting. Next was Snow White, which started to show us how good the rides might be, then Peter Pan, which was awesome.
But it was when we did Haunted Mansion we were really blown away, and realised how amazingly good Disneyland is.