Hard to go wrong with Baduk/Go. Doesn't really scale to groups though.
Terra Mystica[0] and Tzolk'in[1] are both low randomness worker placement game that require long term planning and fun mechanics.
If war-games are more your speed, Diplomacy[2] and Twilight Imperium 3rd Ed[3] are some of the best in class. Both take all day (or more if you play Diplomacy by mail). I personally like Exocus: Proxima Centauri[4] a lot in this genre.