The monkey island series is up there but I remember loving Flight Of the Amazon Queen on my Amiga and I'm not sure what platform it was on but The Faery Tale Adventure, man I loved. I sometimes watch YouTube clips and the music still gets me now.
I don't know if any of you remember BBC Micro games and there was a company which produced about a dozen games called Firebird. One of the games was called Duck! and man, my family loved it. It was probably the only game we used to all have a go at individually, whether you were 8 or 80.
I played this. You can get it free over on GoG. It was a really good game! If you liked that you should really check out Longest Journey. I know i enjoyed both a great deal. Syberia is another great series.