We're planning a short trip to Portland for spring break. We're staying in downtown Portland, and plan to rent a car for one day to go to Multnomah Falls. Is this a halfday trip or a whole day? I really wanted to also see the Tillamook Cheese Factory, but it looks like doing it both in one day is not doable since they're in opposite directions.

Has anyone been to both places? Is one place better than the other?