We did these on different days, but together they'd make a perfect daytrip. To get a lay of the land, this aerial view on the Tug 44 site is worth a look.
The new Falls View Park at Cohoes Falls is fantastic [N. Mohawk St, Cohoes]. (Check the Cohoes Falls Webcam to see if there's water - the image is only updated three times a day - can't imagine why.)
The Waterford Locks are very interesting [park near Broad St. and 5th]. Their Tugboat Roundup is coming up on Sept. 11-13, 2009. I like the views in these old postcards: Images of the Erie Canal in Cohoes - especially this Birdseye View of Cohoes in 1859.
We walked over the bridge from Waterford to Peebles Island State Park [Peebles Island Drive] and did a hike around the island (saw dragonflies, deer, chipmunks, and fish). New York State's Historic Preservation & Conservation Headquarters is on Peebles Island, and they're having an Open House on Sept. 12.
Any suggestions for a good, casual lunch place in Waterford (or Cohoes) would be appreciated - we're tired of the pizza place.