We ended up not going to falls. It was reportedly a very dry summer in the UP, and on the boat trip they didn't even bother pointing out Spray Falls, and we didn't see it. It was pretty prominent from the boat on my prior trip, so it must have just been a trickle this time.
That's what my wife and I were told in Sept when we were at Lake Gogebic. I keep promising myself to hit several UP falls when they are at their flow peak. I'm guessing that might be very early in the year during snow melt. By the time we head up for vacation in Aug or Sept, not much flowing. Get to see a lot of rocks though.