Privateer has always been one of my all-time favorites. It shares a lot of commonalities of the genre: You start out in a wide universe with a broken down ship that you must slowly upgrade and then replace. You get to choose between three ships, specializing in defense, combat, and trade, and you can run goods running from foodstuffs to drugs and slaves between worlds. Eventually you get sucked into a plot that involves (what else?) ancient alien technology. What Privateer has that so many of its competitors lack, though, is atmosphere. Privateer exists in the Wing Commander Universe, so the war with the Kilrathi has already been established, but Privateer does so much more. Landing at a station or planet actually allows you to explore a bit (yes you can actually land on planets they aren't just eye candy). Many of the worlds have their own unique flavor, from the well tended quads of Oxford, to the seedy back alleys of a pleasure planet. Worlds and stations aren't simply docking points that then speed you into space again. Privateer also adds numerous factions, including pirates, traders, the military and a religious fanatic group known as the Retros, each will remember your actions and react accordingly to what you do. Privateer gives you the feeling that you're actually interacting with a real place. Seriously, give this game a shot. It's a fantastic space sim, and a great game.
Sim City is one of those games that seems simplistic and uninteresting on its surface, but has a way of drawing you in, making the hours slip by as you build up your metropolis. Starting from a small village you can build into a gigantic city scape, complete with trains, colleges, ballparks, and, as time passes massive arcopoli to save your futuristic population. Your problems can range anywhere from traffic congestion to monster from outer space attack, and you must combine able planning with budget sense to keep from going bankrupt. It's a deep, complicated and hugely fun game.