Galaxy truckers is fun, until you forget a critical component and lose the front of your ship!!
the lord of the rings, war of the ring game is good (is slightly risk based and lots of minis all in 2/3 colours so may need some base painting) but first play will take somewhere in the region of 4-5 hours (we tried it over 3 and got the ring no-where near the gates of mordor!)
try Smallworld too, the race/ability combos on it are great!!
puerto rico is also another fun one. and i have heard good things about descent as well.
if you can get 4-5 people then cosmic encounters is good