I've never been to Canada before. Any suggestions on things nearby I should see, tips for border crossings, things like that are welcome.
Niagara Falls is certainly an experience, (it's the biggest tourist trap in Canada) there's plenty of things to do and see there.
Like Surely suggested, Niagara-on-the-Lake is a town that prides itself on it's quaintness; while no less touristy, it certainly has a mellower "small town" feel to it. I wouldn't say it's an hour away from downtown Niagara Falls, if you take the Niagara Falls parkway (and don't stop for pictures or to see the Butterfly conservatory) you can make it there in about a half hour from the falls.
Toronto is less than two hours away if you wanted to come up and see the CN Tower!
Border Crossing: Be polite and leave your gun at home.
True very true

I worked as a customs officer in the Niagara area and those two tips will get you far, but I'd be prepared to show citizenship documentation, like a passport or birth certificate. ... I was going to provide you with a link for visitor info, but the Canadian Customs site has a ton of broken links.
If there are kids traveling with you that aren't accompanied by their parents, it's important to have a letter of permission from the parent(s)/guardian(s) and their emergency contact information.
Another general tip, more than just politeness, be direct and succinct with your responses to the customs officer. It speeds things up if the officer can get all the information he/she needs as they need it, sometimes they might ask an odd question or repeat one you've already answered, just answer them again they have a lot to look out for and may need clarification!
Wow I make it sound like a big deal, but most traffic crossings take very little time, it's just that a little preparation can save you a long wait!