Niagara Falls is surprisingly close to Cincinnati. An eight hour drive, mostly on interstate highways, will get you there (make sure you have some cash for the toll road, along I-90). If you are looking for scenic places to stop along the way, consider Geneva on the Lake, Presque Isle on Lake Erie, or Buffalo, New York.
There is often discussion on whether the American or Canadian side of Niagara Falls is better. They both have a lot to offer. However, if you want to get to the Canadian side (and back) you, and your kids, will need a valid passport. Again, keep some change in your pocket for the toll to enter Canada.
On the American side, there are plenty of areas to explore. Goat Island, Luna Island, and the Three Sister Islands offer different views of the Falls and the Niagara River. All part of Niagara Falls State Park, these areas are easily accessed. Whether spending one day or several days, consider the park's Discovery Pass that provides admittance to five different attractions, and an all day pass for the trolley, for a discounted price. The five attractions include The Maid of the Mist (one of the best ways to experience the Falls), Cave of the Winds (another amazing way to experience the power of the Falls), an IMAX movie (currently showing "Niagara: Legends of Adventure"), the Niagara Gorge Discovery Center, and the Aquarium of Niagara (it is not large, but it is worth the visit, and has plans for expansion).
On the Canadian side, there are many places to view the Falls and several worthwhile tourist attractions. Niagara Parks offers the Niagara Falls & Great Gorge Adventure Pass that includes admission to The Maid of the Mist, Journey Behind the Falls, a 4D movie experience (currently showing, "Niagara's Fury"), and White Water Walk, along with a two-day pass for buses and the Incline Railway, and 1/2 price admission to other attractions.
Also on the Canadian side are Marineland, the Skylon Tower, and Clifton Hill. Marineland is a large park, with a lot of walking between attractions, but a worthwhile trip to see the Dolphin Show, the Killer Whale Splash Show, and the lovely Beluga Whales (it costs extra to feed them). Marineland also offers several amusement park rides and an arcade. Skylon Tower presents a glass-enclosed exterior elevator ride to the observation deck, 775 feet above the Falls, as well as two restaurants. One of the restaurants features a revolving dining room. Both restaurants have early bird dinner specials and coupons available, admission to the observation deck is included with dinner. Clifton Hill is full of activities, restaurants, and accommodations. Galaxy Golf provides glow in the dark miniature golf. Guinness and Ripley's entertain with the bizarre and hard to believe.
Parking the car ($) and walking is the easiest way to travel on both sides, although some of the hotels offer shuttle passes which can be a great value. The Rainbow Bridge provides vehicular and pedestrian access between the U.S. and Canada and gives a great view of the Falls. If walking across be sure to take your passport with you.
There are many varieties of accommodations in Niagara Falls. Several newer hotels boast of rooms with views of the Falls that allow you to see the weekly fireworks and nightly illumination from your bed. Many offer breakfast, swimming pools, tour services and more.
Niagara Falls offers a relaxing vacation, with most of the time spent outdoors enjoying the majesty of this natural wonder. It is a family adventure waiting for you!