I've only used nukes once. The setting was diety, on a huge map with 16 civs left (archipelago, 70% water). By the time nukes came, there were 10 civs left and everyone had a military alliance against everyone with mpp's pulling everyone into unwanted conflicts, including myself. There were two superpowers - myself as the Great Tokugawa and the communist bastard Catherine of Russia. It was my belief that Russia was the aggressor, as most military alliances were tied with her against, well, everyone else. There hasn't been peace since the Middle Ages, I swear. I decided to end the war as soon as i bought the tech for nukes from my Chinese buddies, and immediately switched my capital to the Manhattan Project and switched my productive coastal cities to subs. As soon as I could, I pumped out as many ICBM's and Tactical Nukes as I could for the next ten turns, most of which were made of gold (my science was at 10% the whole game and I bought about all my tech). As nobody had any money, and some cities on both major landmasses switched between 4 different nations, and I doubt anyone else could build nukes as my productive home island was never before invaded (well, successfully anyway), I thought I could end the war in one turn with my 30 or so nuclear warheads. I completely turned Russia into a wasteland and razed the majority of their cities (I sure as hell didnt want them). Two turns later everyone was at peace as I think I scared them all to hell by turning Russia into a nuclear winter wonderland, although my rep was shot as a result of my many Hiroshimas, yet I never saw a nuke fly over my great empire. Well, anyway, thats my nuclear war.