Here are some things to know before you visit Niagara Falls:
The hotels with views of the falls on the Canadian side are a lot more expensive than hotels only a little farther away (with no view). We stayed at the Embassy Suites, where there was also a valet parking fee of $35/day and the taxes and fees added to the already high room rate were exorbitant. I really like Embassy Suites for their comfortable rooms that can sleep 6, and their fantastic breakfast, but in this case the price was outrageous. I would stay down the road at a fraction of the price (and free parking). I do not know how hotel rates compare on the American side.
The waterfalls are lit up at night, but they turn off the lights at midnight. They also have a fireworks show Fridays, Sundays and Holidays at 10pm from May-October.
If you stay on the Canada side, you need passports. Crossing the border took almost an hour (in August), both directions. This time could vary significantly, depending on the season.
The Maid of the Mist boat ride was really fun and you get great picture-taking views from the bottom (until you get to the mist–then you don’t want your camera ruined by water). It was $20 per adult ($15.50 on the American side) for a 1/2 hour ride. The boats go every 20-30 minutes, so the wait time is not unreasonable. (I guess it could be longer on peak days). It took us about 30-45 minutes to get on a boat. Summer hours are roughly 10am – 7pm. Check the website for current info: www.maidofthemist.com
We felt that a half day was plenty of time to see the waterfalls. There are a lot of other things to do there, but they are mostly things unrelated to enjoying the natural beauty of the waterfalls. Many families would enjoy these activities and they could keep children entertained for several days.