Taughannock is the tallest falls hereabouts, and the gorge is deep and dramatic.  Most-travelled is the relatively short and flat gorge trail, but the rim trails on each side offer more exertion and very nice gorge views below and above the falls.  The lower park is accessible from Route 89, while the upper park can be reached by following the signs from Route 96 near Trumansburg.

Links for Taughannock Falls State Park:
http://www.taughannock.com
http://www.naturalhighs.net/waterfalls/falls02/taugh.htm
http://www.priweb.org/ed/finger_lakes/taughannock_falls.html
http://gowaterfalling.com/waterfalls/taughannock.shtml
http://images.beggerlybend.com/photos/gorges/tf/index.html
http://nysparks.state.ny.us/parks/info.asp?parkID=93