Having not been since I was much younger, my girl and I gave Ontario Place a whirl. I was skeptical, as I wasn't sure if it would suit people who were going without children.
Ok, so it's no Wonderland, but I actually found myself having a lot of fun. The weather was gorgeous, and just getting to walk around lakeside is a treat for someone who doesn't get out that way very often. The casual atmosphere (versus the crazy lines and ride-rush of Wonderland) definitely fit the situation as well.
As for the attractions there...well there aren't many. We did the log ride a couple of times (which was not how I remembered it AT ALL), as well as the 4D theater, which was fun...I even got water squirted into my ear during the thrilling underwater scene. Good shot! The mini-golf was also fun, and was included with the Play-All-Day pass.
We also hit up the water park section, which I didn't remember from my youth, but was really fun. We did the single-person slide once, and the 2-person tube slide a few times, which was really fun, if not much different from Splash Works at Wonderland.
All in all, a really fun day. Sure, it doesn't have the flashy rides of Wonderland, but it also didn't have the insane crowding that goes along with that. I was looking for a nice relaxing day that allowed the chance to enjoy my company and do a few fun things, and I got exactly that.