Our youngest daughter and I had a wonderful time riding the Duchess Rail Trail over the Hudson River the other day. We left from Hopewell Junction, and round trip, across the Hudson and back, it was 28 miles. (Our daughter, however, rode 32 miles, because she doubled back to the car for money for treats on the bridge.) To me it felt uphill both ways (you can even see it in the photos?) which I guess means it was flat most of the way.
The photos here were all taken with my iPhone5, since whatever cargo room we had we allotted to homegrown peaches and water. I recommend you adding this fun bike trip to your bucket list!