Three months late, but better late than never. btw, Colonel - you working on an epic mod? I've been organizing one for about 2 months now. I'd be interested in hearing your thoughts, or maybe helping you out. It's much more demanding than a scenario...
ROAD MOVEMENT
I set movement on roads to 2 which is much more realistic.--contributed by Weasel Op
I agree with this. Double the movement on roads still adds favorable value. It benefits more when thinking about scouts. Typically a scout is the master of terrain as well as having efficiency in travel (they know the area & the shortcuts). This means they should receive "treat all terrain as roads." Now, setting them to 1 movement, means 2 moves on roads, 2 moves off roads. Non-scout units (with 1 movement) then would be equally fast on roads, but struggle off roads, which is a fair assessment.
Techs going too fast? Some techs being traded too quickly amongst the AI? Set them to non-tradable. Make
all the Civs discover Nuclear Weapons, just make sure
you're the first

- but watch out, they can still steal the technology.
Sure, there may be igloos in northern Canada, monk temples in Tibetan mountains and casinos in American deserts, but in 90% of the rest of the world those areas are bare (or at least there isn't 1 million population in a particular area). If they aren't - sure seems to be common ground for terrorists or other non-conformists. Try making tundra, desert, and mountains into colonies/outposts only - no settling. If you surround the area your culture will cover the lands, but if you don't - you'll have your own al queda network in your backyard - keeping you on your toes even late in the game.
RESOURCES
Discourage that starting human-controlled settler from wandering to find an ideal starting location (afterall, the AI doesn't). Make resources require something, cattle requires domestication, gems/gold require mining, game/furs require hunting, etc.
UNITS
Got a specialty unit (sniper, special forces, etc) that is too hardcore to just let the AI & humans freely build? Make it auto-produced from a small wonder - that way each Civ can only have one building pumping them out every 10, 15, maybe 20 turns. Exploit
that!