I'm looking for guidance in Civilization IV on how best to build a military that allows for the optimum mix of defensive capabilities with offensive ability (when needed) without having to sacrifice technological gains and city improvements.
Some background: I'm having difficulty balancing domestic output and city improvements with military strength and aggressiveness whenever I play at the Noble difficulty level or above. My preferred style of play is to not emphasize military strength, but instead to work on science and trade and city improvements. On the military front I build primarily defensive units with defensive city improvements (such as archers and walls in the early game). The problem I run into with this strategy is that usually by 0 AD or so there will be at least one civilization on the map that's got it out for me, despite my attempts at placating all of my neighbors. They'll send in a swarm of units, destroy my improvements, and take out a few cities. My only defense (sadly) is to buy/negotiate a peace treaty.
I've tried playing the opposite way - building a very strong military - but in doing so I usually have to sacrifice building workers/settlers at the rate I enjoy, which slows my expansion. I usually last a lot longer but by the mid game my civilization is behind most others when it comes to technology, city sizes, the breadth of my empire, culture, and so on. Also, this approach just isn't as much fun for me.