The thing that I would really like to have in the game, at least once in a while, is the joy of letting your powerful units rip into the enemy (one of them at least). Currently, you're constantly playing the role of the grown-up, which is unique, but also lacks a certain... Joie de vivre?
Here's the idea: every once in a while, you get a random mission/bet from some god. "I bet you can't destroy 4 Norse giants in 10 turns!", "destroy the Greek city of X in 15 turns", "wipe out Norse civilization (after which I'll give you a free Norse city center) within 20 turns!". These missions could either be optional or mandatory, and they would give you a hefty score reward for completing them, and possibly a penalty for not doing so. Rather than just woes creating the imbalance (and having all the fun) you would be the one doing so.
Whaddaya think?