Good call on busting out Carcassonne. One of my favorite Euro-games - it's simple to learn but surprisingly deep, and isn't completely cutthroat like Risk etc.

Have you played Settlers of Catan? That's my all-time favorite board game (needs 3-4 players). Great fun trading and building game, with little opportunity to actively screw over your opponents (though there are still some opportunities for mischief).