Bohanza is an outstandingly fun game of bean trading that has never failed to pull people in.
I'm a fan of Bohnanza, but my fiancée dislikes it strongly...
It takes a lot of getting used to, not being able to rearrange the cards in your hand.
Killer Bunnies and the Quest for the magic carrot is a very good game for socialising - the trick appears to be to not actually try to win! The longer the game lasts, the more fun it is - we've played with people who are determined to 'win' and it tends to mean shorter, less interesting games.
I like Killer Bunnies strictly for the craziness of all the expansions. Every card and bit just barely fits into the original blue box, when you take out the insert (see attached pic).
The game has some glaring problems... First, it tends to take way, way too long. I'm not a huge fan of it in the first place, and I flat out refuse to play with more than 3 other players.
Second, there's a lot of major ambiguities. A lot.
Third... Shuffling the game is... an experience. Generally, the only way to shuffle it is to clear off an entire table and get all the players to push the cards around the table for a while.
All that said, I still enjoy the game on occasion, and I'm glad to have it.