The Adventure Genre is one of my favorites, srsly loev pixelhunts and pointnclick. Conversation trees make me wet. Pretty much any Sierra game with "Quest" in the title is worth playing. If you haven't played a Monkey Island game, you need to set yourself on fire right now because you don't deserve to live anymore.
I love the Sam and Max series, but their puzzle solutions are often times nonsense, and require randomly combining inventory items, but the stories, characters, and everything else about the series is amazing.
Full Throttle was awesome, Grim Fandango, and The Longest Journey are good too. Those should be some other ones to check out if you've never played them.
You should go look at GameTap, and look at their subscription plans, you could probably get a freebie somewhere, and quit in a week when your binge is over. They had a lot of adventure games there, IIRC.
Also, jayisgames.com is a gaming blog that is sponsored by some game companies or something, but they often have deals on adventure games, among others.
Edited, Jul 20th 2009 12:57pm by NixNot