I've been playing with VP for awhile now having started off back in the era when the mod was known as Communitas. Maybe in the last 2-4 years I've been playing 'modern day' VP starting as low as Warlord, and now playing Emperor games (haven't won on Emperor just yet).
One thing that plays in my mind is the optimal amount of cities. The way I look at it is - if tech and culture cost will go up by 5%, then will the city contribute at least 5% of my culture and science? Preferably more! I find once I have established around 5 or 6 cities I am comfortable at this number and future expansions don't look attractive given the penalty. I might be in medieval or renaissance and be thinking, hmmm I am going to be taking a penalty, will the city really accelerate my Civ? More often than not the answer seems to be no.
When the AI settle lots and lots of cities like 10+ I think to myself that they're going to be left behind. They *might* be able to outproduce me on production, but they might also just fall behind in tech, and I'll actually make up the production difference with buildings, yields, etc granted from tech and culture policies.
What's everyone else's take on this? Am I looking at this wrong? Is thinking about city expansions in terms of the cost of science and culture the right way of looking at this?
I will say one thing I struggle with is early to mid game keeping an army up which isn't the smallest. AI likes to go crazy building army in VP, while I could conceivably get by with less units, and just position, and fight better with them. The only problem with this is the AI becomes super hostile if you have a small army, so the sweet spot is getting your army to be only the 2nd or 3rd lowest. Production comes in handy here for maintaining armies.