My best fun with civ4 came first when I was learning the game, then later when I was learning FFH. I enjoy min-maxing and microplanning and getting four cities with six workers and 20 improved tiles by turn 60, or beating the AIs back on Deity*, but not nearly as much as I did when I was learning as I played. I haven't finished a single-player game in over two years not only because I am somewhat time constrained.
*Technically, because I haven't played a SP game in so long, I have never won nor even finished a Deity game, but I am a lot better than I was a year ago, and I was competitive on Immortal back then.
*Technically, because I haven't played a SP game in so long, I have never won nor even finished a Deity game, but I am a lot better than I was a year ago, and I was competitive on Immortal back then.