DON'T LOOK NOW is a good choice. That movie has such a creepy vibe.
MichaelS mentioned LEGEND OF HELL HOUSE. I can remember watching that as a kid, my older siblings were babysitting me, and they let me watch it. It got to my bedtime and I refused to go to bed, so the compromise was they would let me stay in the TV room, but they held a blanket in front of my face so I couldn't actually watch the last half hour. When the ending revelation happened, I still remember their frightened reactions and that scared me more than if I had actually seen the movie!