Taughannock Falls State Park is one of the most popular parks in the Finger Lakes area of Upstate New York. The major attraction for most people who visit Taughannock Falls State Park is the waterfall itself. Taughannock Falls (pronounced tug-ANN-ick, believe it or not) is the highest single-drop waterfall East of the Mississippi River, and it's a breathtaking sight. To visit the falls, you can either stop at the Falls Overlook (on Taughannock Park Road in Trumansburg, New York) or park your car in the lower section of the park on Route 89, where you'll find a nice, easy 1/2 mile trail waiting for you, or, if you're a more fervent hiker, you can try the "rim trail," which sends you up the top of the gorge. My preferred way to introduce new friends to the falls is to walk the lower trail and see the falls from the bottom (the only place you can truly understand their enormity!) and then stop by the overlook on the way to lunch, to get a view from the top.
Taughannock Falls State Park is not only home to the Falls, though. There are also two separate waterfront sections of the park: North Point and South Point. South Point is a bit more recreational. There are lifeguards in the summer, if you'd like to go for a dip in beautiful Cayuga Lake, and the Park's popular summer concert series takes place at South Point as well. South Point is also home to the boat launch, so if you've brought your boat or jet-ski along with you from home, that's the place to go to launch it into the lake.
North Point is a bit more picnic-friendly and private, I find. I also find the beach to be a better place to skip stones, which is one of my favorite Finger Lakes activities (the wide, flat pieces of slate and shale that make up most of the beaches are perfect skipping stones).
Taughannock Park offers both tent and RV camping sites and rental cabins, and there are a variety of nearby bed and breakfasts and hotels, if you're not a fan of camping. For more information about the park, you can call (800) 456-2267.