I poked around the 'net a little and found out that an 8-hour game is totally normal. General sense is that it's a 7-12 hour game, especially with 6 players. So the '4 hours' on the box is a complete LIE.
I also found a couple essays on strategy, including one on the particular race I played. I was gratified to determine that I actually did pretty well, given my situation. The Yssaril have very low initial production compared to everyone else, and in last night's game I ended up being surrounded by low-resource, high-influence planets. So there really wan't any way to make up for it, and about halfway through the game I suddenly realized that everyone else had fleets that were two or three times the size of mine. So needless to say, I wasn't really anywhere close to winning by the end of the game, but I had taken the general approach that the essay recommended, and I did avoid all of the pitfalls it warned about, mostly having an unarticulated instinct that they were things to be careful about.
Experience with 4X games (I've been playing MoO again) is fairly generalizeable, because it's all about feedback loops. The more resources you have, the more you can use them to get more resources. So it's exponential growth, and winning is mostly about finding ways to push yourself up the curve as fast as possible, because once you're far enough ahead of everyone else, it doesn't matter what the win condition is, the acceleration factor has magnified your lead enough that you can do whatever you want.
I could probably say something noteworthy about the applications to real life here, but I'll just point out that, hey, positive feedback gives you exponential growth, and that's an important effect. It's also something our naive instincts are pretty bad about.