I’d already managed to sneak in my list of the P&C adventures I played fairly recently (in order of release) and I found all of them enjoyable enough. The best from the list (and the best ever!) must be Memoria, however. That was the first ever game that touched me deeply, and made me cry at the end. That alone qualifies it for instant #1, but it’s also executed very well. If you speak German, I highly recommend the developer commentary from the fantastic Kevin Mentz (after you played the game, of course!).
As for older adventure games: I liked Legend of Kyrandia, Simon the Sorcerer, the first Discworld game. Afterwards I kind of turned my back on the genre (the Lucasarts stuff aside). The first one I really enjoyed again was Tales of Monkey Island. Shortly after that I replayed MI 1 and 2, and must say I liked Tales more than MI 1. My humour must be different now than it was at age 12 :-).
Me too, though it was my wife’s DS ;-). Two more remarkable DS games, that fit the category were Hotel Dusk: Room 215 and its sequel, Last Window: The Secret of Cape West.