Originally Posted by Caddy 
Really any of the Master of Orion games (although I haven't played 3, I hear it's lame?)
3 is actually not bad in multiplayer, but in singleplayer, the braindead AI make it a poor game. That, and there are elements that don't seem to work properly, which the AI don't know don't work…
In most 4X space games you'll sooner or later end up at a stage where you'll have to confront the AI, or alternatively, have a big enough fleet as to deter the AI from attacking you (more often than not, both). This is true for Master of Orion, Galactic Civilizations, Endless Space, Stars! and any other 4X space I can think of. But at least you don't have to deal with tactical combat in these games. Sword of the Stars can also be played with automated tactical combat (get the first one, not the second one).
Actually, I think you might be able to play
Aurora in a non-violent way, but Aurora is just amazingly complex, and I was never able to get into it (Aurora is, by some, described as "being to Dwarf Fortress what Dwarf Fortress is to other games").