I would recommend The Longest Journey and its sequels - Dreamfall:TLJ and Dreamfall: Chapters.
I've managed to beat them without walkthrough, unlike Syberia.
The Longest Journey is definitely one I'd have put in if you hadn't.
Regarding its sequels and that is speaking for me, I absolutely totally hated the trolls/cave bit, to the point of swearing and screaming insults at those things. Though I know some others where in the same boat, whether I/we just plain sucked at that section or it just sucks all by itself, dunno. As much as I loved the first one, despite having saves for those personally hated bits, haven't replayed the others.
Staying with the classics you can find here and not already mentioned, Runaway was a fun one.
Also The Dark Eye: Chains of Satinav and Memoria are worth mentioning as well I think, they have (both if memory serves) hotspot and combination indicators.