8. Carcassone (w/ expansions)
This game is a classic, and a beautiful one at that! Mechanics are fairly simple: place a tile, place a wooden meeple on that tile, score points; however, the strategy is very strong. Especially when playing a two player game, it is both fun and intense trying to form the map just the way you want, block your opponent, and predict what tiles will probably come up next.
However there is one caveat, make sure that there are a lot of tiles to go though. Not that I am saying that it is necessary to use all of the tile provided in the Carcassone Big Box set, but I think that it is essential to add one or two expansions and make sure that there is enough options for the players. Especially if you are setting up a game for four or five players, using just the tiles from the base set really detracts from the best qualities of the game. I am especially observant of this point because I was reluctant to play in the Carcassone tournament last year at the WBC convention because of the possibility of getting placed into a game of five players with only the base set. 71 tiles to be drawn divided by 5 players results in only about 14 tiles per player over the entire game.
Nevertheless, with the addition of expansions like Inns and Cathedrals and Traders and Builders, this game becomes one of my favorite games to bring out with many different people, friends and family with different backgrounds of board-gaming experience. In short, I think this is certainly the best gateway game, as many board-gamers would call it.