I was raised on King's Quest and Quest for Glory, all of which I have beaten, and all of which I enjoyed, probably because I didn't know any better at the time. I just figured all computer games were fiendishly hard. Before all the Sierra goodness, I played text-only adventures (which I can't remember EVER beating), and some old 5.25 disk game called "Demon's Forge," where my only memory is throwing a blanket on an assassin before he shoots you.
My embarrassing confession is that the ONLY LucasArts games I have ever played were Out of This World (that's LucasArts, right?), Day of the Tentacle, and The Dig. I've never been to Monkey Island, hit the road with Sam and Max, gone anywhere Full Throttle, been trained to use the Loom, and I've never entered Maniac Mansion, not even with a remake. I don't even remember hearing about Grim Fandango until I started hanging out in the forums here.
But even being one of the Sierra faithful, I've never played Police Quest or Leisure Suit Larry, either. Not that I regret missing out on either of those. My Sierra favorites were QfG3, KQ6, and Gabriel Knight 1.