After playing more games, I thought, wow, I forgot how overpowered Communist Utopia is!
Looking at all the zone cards in the base set, most of them give a bonus worth $2-$4 under the right circumstances. But there are a few zones that give a bonus of $8: Communist Utopia, Information Age, and Space Age. And they're not even that hard to trigger.
In the expansion, the standouts are: Floating Cities, Dutch Golden Age, Tibetan Empire, and all the hourglass zones. These are much harder to benefit from. I haven't gotten Floating Cities to work at all yet.
Also, in the base set, the swingiest cards are probably the powerful perpetuals, like Gang of Pickpockets or Conspiracy. When you draw one of these at the beginning they can do a lot for you. But the expansion seems to have more perpetuals that give you flexibility bonuses rather than value bonuses.
Overall, I think the expansion reduces the amount of luck, and pushes more careful planning.