You mentioned Leisure Suit Larry and King's Quest so I'm going to suggest Botanicula. It's a beautiful and very kid friendly point and click adventure. http://botanicula.net/ you can even play a demo right there in your browser. I played it a lot with my 7 year old sister and we had a blast.
I guess your question has mostly been answered by now - but difficulty also really depends on genre.
Personally - I find every platformer hard, even back in the days when I had unlimited lives on Great Giana Sisters.
I just finished Botanicula - unbelievably entertaining, almost cried at how beautiful and cute it all was, and then had to watch a Jeffrey Dahmer documentary to uncleanse myself.
Try Botanicula, a new point & click adventure game from a well-regarded indie studio.
It takes place in a forest/garden, and explores the full range of life forms in a very surreal and otherworldly way. Definitely the most alien game I've ever experienced.