Exactly, the first policy-tree is about how you start your empire, second one is focused on victory-condition and the third on how you want to finish the game. Ideologies are somewhat tuned towards different victory-conditions, but they are mostly a matter of flavor, and how they complement the rest of your choices.
As for the Parthenon only being decent if you choose to purpose tourism, I still don't agree to this, and I know Gazebo don't, he have been going through a whole lot of work to make sure tourism is a viable yield outside of culture-victory, and making tourism a part of the game you shouldn't really afford to ignore (kinda like science, military, culture and to some lesser degree city-states).