I don't know if these count, but Mortville Manor and it's follow up Maupiti Island are my all time favorites in adventure gaming. The mood and atmosphere they generate are excellent.
They were certainly ahead of their time, using speech synthesis and view screen point and click manipulation of objects. I also like Shadowgate, Uninvited and Deja Vu which are along the same lines, but Mortville Manor makes me feel more like I'm really there with better control of my surroundings.
I prefer these titles over the 3D sims of today. They're more like chess games than just running and shooting. They give you the time and ability to contemplate your moves...