Help Planning the Pacific Northwest tour 2014!

How old are the kids, and how far can they hike? For example, there are lots of amazing waterfalls in the Columbia Gorge, just a short walk from the parking area, and they are at their peak in late June and early July. Some of them (like Tunnel Falls on Eagle Creek, below) require a longer walk -- but how often do you get to walk right behind a thundering waterfall??