After reading this thread I checked out Sierra on wiki and read up on their history.
Gabriel Knight 1 looks pretty good. I might try and get my hands on it. I miss the classic AG 2-D style, so I wouldn't mind searching out a few classic games.
The only non-lucas arts game I ever played back in the day was Rex Nubular. I remember thinking it was really weird when I was a kid, but I managed to get pretty far.