Thank you all for your comments and suggestions.
Geoff:
I don't care much for the tone of the sky peeking through the leaves either, but I like the low vantage point on the falls and the trees at the top of the frame, so I was willing to make the tradeoff. As for lighting, there is a fairly dense tree canopy over the stream, so the area gets filtered light for most of the day. On my next trip I'll try the polarizer and blending exposures to help the color and shadows. And maybe that pesky sliver of sky, too. Different time of day may help as well.
New_Haven:
I like the warmer look, but I think you went a couple of clicks too far for my taste. I like what it does for the trees and rocks, but I'll try masking the water to as not to accentuate the muddiness in the foreground.
Thanks again for all the suggestions - there's lots of rain in the forecast here, so plenty of opportunities for a re-shoot.