What settings are you playing with? I play Monarch with Fractal Map, moderate climate, and I thought defaults on everything else. (I face six other AI's) I must get a good start point and even then I can only win maybe 5-10% of the games. I don't culture rush, and I find the AI's very competitive with all the bonuses they get. Usually a Civ on another continent gets it to easy and runs away with it, or some Civ culture rushes me and I can't get strong enough to stop it. I have been playing for years and the only boredom I face is if I go for a military victory, which is often not even an option.
I am almost half way though the Civ list trying to win each on Monarch.