Grim Fandango was pretty cool. The humour in adventure games really is what makes them imo.
I don't know a single one where there haven't been a few moments where I've burst out laughing at something said.
Really I think the best examples of how the Genre has evolved are the Monkey Island Series and Broken Sword Series.
Both are irrifutably landmark mark games of the genre, like Doom / Half-Life are for FPS.
While I do really enjoy the old point'n'click interfaces, Monkey Island 4 and Broken Sword 3 have shown me that you can effectively make these games with them being just as much fun in 3D.
The evolution does open up new possibilities, well once these companies fix the annoying Camera Switch problem.. it's frustrating exiting an area just to run right back into it heh
2D Gives artists far more freedom in terms of what they can create visually. 3D however is capable of adding an extra dimension, especially from a Controller input device.
Broken Sword 3 for example, albiet a lil too short; provides the gamer with some new style of gameplay.
Objects are still used in bizzare manners, and the character interaction is still very much there providing you with different question avenues; but the ability to traverse a 3D environment; sort of like a Grid'Puzzle version of Tomb Raider is pretty cool. Especially when you still have some classic puzzles like pushing stones to block spikes from making you a human sish-kabarb, or using multiple items in an order to get a door to open.
New action elements in the game also provide more of a 'actually there' feel. Like at the start you have to press the action button at just the right time to stop from getting shot.
Both varieties have thier upsides and downsides. Personally though I would say I lean towards the 3D Adventure Game
there might not be many of them, but those that are, really do stand out quite well.
Something particularly impressive with Broken Sword 3 really is the graphics; dynamic shadows & light, radiosity lightmapping, if it weren't for the poor shading effects on the characters themselves and poor animations the game would definately be one of the most polished i've seen.