Having explored the web sites for the Hudson River Trail and the Dutchess County Trail, it appears they are both the types of trails my wife is not crazy about. She prefers trails that pass through lots of quaint little towns we would never discover in a car. I, too, have grown tired of the sameness of virtually all the rail trails I've ever ridden. Don't get me wrong, the Wallkill Trail is gorgeous, and the others seem to be, as well. But once you're sandwiched between 2-3 miles of trees, they all look and feel the same.
That said, we might not mind doing a little "highway" riding or exploring some towns off the beaten path as an excuse to ride the Walkway.
Thanks for the info!