If you want hard puzzles:
Runaway: A Road Adventure
I'd recommend Sam and Max (both the old game and the new episodes), but it's nothing like any of the games you listed. If you're wanting to broaden your tastes a little and you like witty repartee and satire, you'd like it. If you're willing to wait a little while, SBCG4AP is even funnier IMHO.
I've heard good things about The Longest Journey. I can recommend the Gabriel Knight series, especially the first. Not so much the third, though. It sort of suffers from Simon 3D syndrome.
Myst like, hrmm...
If you just want straight up puzzles, Entombed is pretty good (though strictly not an adventure).
Heart of China kind of has a Myst perspective. It also has cheesy dialogue, a corny storyline and overacted (hammy!) characters.
The Last Express has a sort of Myst-ish perspective and features rotoscoping. It's greatly replayable because the environment changes depending on how you interact with characters, and the game branches very frequently. Moreso than in most other adventure games I've played. Also, it's by the Prince of Persia guy.
Finally, Murder on the Orient Express was one I enjoyed recently. The Agatha Christie games feel a bit cookie-cutter, but they have good stories that work well as very linear games. If you want a quick game, I'd recommend one of those.
