Back in the day, "foreign travel" meant a journey north from Pennsylvania to Canada. Despite numerous excursions to places like Montreal, my parents never quite took my sister and I to the Canadian side of Niagara Falls. It was within sight as we visited the New York, USA side, but as a youngster country boundaries had little meaning and we were caught up in the spectacle that is Niagara Falls, no matter which side you are viewing it from.
I still remember wearing my rain coat to experience walking on a boardwalk at the bottom of the falls, hearing the thunder of water while watching the "Maid of the Mist" excursion float by us.
View of Niagara Falls, Ontario from the NY/US side. 
A few years ago, the stars aligned as we found a hotel coupon on Groupon at the same time two grown "kids" and mom had clear work schedules, enabling the next generation of family to travel to the Canadian side of the Niagara Falls.
A quick overview:
The view of the falls is spectacular, day and night. The USA never looked so good!
Be prepared for kitcsh and cheesiness (example: Giant King Kong hovering over the Burger King and a volcano erupting behind a T-rex) on a main street.
Take part in at least some of the kitsch, even if you aren't there with kids/grandkids.
Enjoy some adult time (music in local gathering spots and bars).
Get a little wet (all the same type of excusions as the US side, including Journey Behind the Falls and the Hornblower cruise).
Explore closeby attractions (Bird Kingdom, Power Plant, ziplines, and much more).
Explore beyond the city (drive to Niagara on the Lake). Trust me on this.
Our hotel was the Sheraton Fallsview, situated at the bottom of Clifton Hill (more on that below). Aside from glorious views of the falls and a room with both a whirlpool tub and a fireplace (not used or needed in June, but still!), it was convenient to most everything we initially wanted to see. My only issue: the hotel offered us a free upgrade when we arrived, which we took without question. The upgrade resulted in the fireplace and whirlpool tub, but dropped us to the fourth floor, taking away some of the view of the falls. Lesson: pick your priorities and ask questions. In front of the hotel is the Oakes Garden Theater. It only takes a few minutes to stroll through and was easily done as we were headed to the Falls Promenade. The gardens are small but can transport you to another era. It includes a Japanese water garden, a curved pergola that looks down on an amphitheatre, and the Secret Garden Restaurant where you can eat breakfast or lunch on a outdoor patio with the falls in view (note: we did not eat there so cannot yet testify to the food, but the menu looks good and reasonable. One of our rules for travel is to never eat at a restaurant that is immediately on or abutting a tourist attraction. We like to go where the locals go).
During the day, we could walk to the falls activities, or across the International Rainbow Bridge to see the view from the midpoint, or all the way to the Niagara Falls State Park on the NY side. (Note: if you do this, you must go through customs and border patrol. Have your passport on hand and be prepared to wait just a few minutes to be processed).
The hotel is also connected via an indoor walkway to an entertainment complex that includes a The Fallsview Waterpark with 16 indoor waterslides and Adventure City, which has over 125 arcade-style games. Connected on the first floor is also a small shopping area, wine store, and a bar with live music, among other things.
In the evening, we could view the fireworks from the hotel's upper stories (spectacular), walk along the falls, take in some music at the Niagara Brewing Company (attached to the hotel) or sip a libation at the wine bar.
This area is also home to Clifton Hill, known accurately as the "Street of Fun" and the ultimate center of amusement and kitsch. If you approach this with the right attitude (accepting the glitz and over-the-top attempt to get your attention), and temper your (or your kids') impulse to do the first thing you see, this is a great place. It was tempting to go wild, but per mom's sensibilities and with advance warning to my family, I limited us to 2 attractions. Be aware that there are several competing "groups" of attractions, including Niagara Fun Zone and those on the Clifton Hill website (owned by HOCO Entertainment). Both sell ticket packages online and in-person, and you may also buy single tickets for an attraction.
We did the Mirror Maze (part of Niagara Fun Zone) where I was both the worst mom ever (laughing and taking photos of my son as he smashed into several clear pieces of glass) and best mom (I cracked up at myself and entertained my family as I smacked right into a glass wall while taking photos of them). Kitsch but fun.
Next up was the indoor Glow-in-the-Dark mini golf. Attractive selfie taken with my daughter, who is the proud owner of straight, white teeth. #ProudOrthodontiaParent
SO many other interesting attractions around downtown Niagara Falls, Ontario which we saw but did not do. Newbies that we were, we did not plan enough time there. Among the attractions in the immediate vicinity is the Wildplay Zipline To The Falls, and Skylon Tower.
As an avid bird watcher, I take every opportunity to visit aviaries and I had read that nearby Bird Kingdom is, in their word's, "The World's Largest Free-Flying Aviary." I was skeptical when I stepped in the door to the small lobby/gift shop, but the facility did not disappoint. From getting the macaws and parrots to follow our antics to feeding lorikeets from our hands (and having them land on our shoulders), we had many encounters with our feathered friends. We delighted in the main aviary where we were able to get up close and personal with many of my favorite birds, including the Victoria Crowned Pigeon (see photo and end of the video--and excuse my fawning over and talking to every bird).
Ultimately, the things that surprised me:
1) The many opportunities to hear live music, in venues with or without kids.
2) How you can quickly switch from one environment to another of your choosing (relaxing in a seemingly remote garden then walking up the street to Frankenstein or down the block to a inspiring view of the falls).
3) The range of focus from entertainment to educational to adventure opportunities within 20 minutes or so will give everyone in your party something they enjoy and feel comfortable with. A trip back is definitely warranted. My goal is an adult weekend with my husband out by Niagara On The Lake. Please note: this trip was pre-pandemic. Check Canadian and facility requirements (if any) before making plans.