We had a really fun time on our road trip! My biggest recommendation is to BRING HEAVY-DUTY BUG SPRAY for the hikes. The guide recommends this but only in the booklet for the stop, which you aren't supposed to open until after you've already left home. We went on a hot sunny Friday in July and none of the stops were overly crowded or too busy.
The first stop (we did the "coming from GTA" option) was nice but we found ourselves wishing there was a bit more guidance on fun things to do or see rather than "cafe/brewery/park" and didn't spent much time there.
The second stop was a nice forest hike but again, we were being eaten alive because we didn't bring bug spray so we only did the short trail.
The third stop was very lovely - make sure to visit the park and beach area. I would not recommend the (Local) Brewing Company restaurant - like someone else also mentioned, service was terrible even though it was not very busy. We almost left before ordering because it was so slow.
For the fourth stop we opted for the hike by the river which was very beautiful as the sun was beginning to set.
This is a great one-day road trip from the Toronto area that could easily be lengthened if desired. Highly recommended (don't forget the bug spray!).