Most places will be difficult to access with a stroller. You might consider a child carrier (backpack) instead. My wife and I have something like this (link below) and can make it to most of the climbing areas.
http://www.mec.ca/Products/product_deta ... 0647277683A motorhome would be an ideal way to get around. Lots of campgrounds provided you come between May and October. November to April are cold and icy.
Places that are worth visiting on your trip for climbing are listed below. There are several other spots but these are the highlights.
Lions Head, OntarioThese limestone cliffs are located on the Bruce Penninsula 4 hours (?) North West of Toronto. Most of the climbing is sport but you have to rappell in then climb out. This may be a difficult area with kids unless you have help from others.
Niagra Glen, OntarioThis fantastic bouldering destination is located just below Niagra Falls 1 hour (?) South East of Toronto. There are trails here that would be accessible with a stroller but you'd have to carry it down some stairs first. It can get hot here in summer. September and October is best time for climbing here.
There are currently talks about closing this area for climbers. Check before you go.Val-David, QuebecSituated about 1 hour North West of Montreal. Great climbing on granite cliffs. Some sport routes but mainly traditional climbing. There is also some bouldering here but I've never tried it. I hear it's good. There are climbing fees here. Come prepared with cash there will be someone at the trail head selling tickets.
Kamouraska, QuebecFantastic sport climbing with lots of easy routes well protected climbs very scenic view. This is a must do if you enjoy sport climbing but you'll want to bring some help. There is a campground nearby and they also sell passes for the climbing. Unfortunately, you will encounter fees for most climbing in Quebec.
Welsford, New BrunswickLots of climbing here on beautiful granite. Found 40min South of Fredericton. No crowds so you'll have lots of peace. Most of the climbing is traditional but there is one smaller cliff with lots of sport routes but not as nice as the main cliff. No fees for climbing. Free camping. You can park your motorhome near the climbing. Again, need a child carrier (backpack) to access these cliffs.
St-Andrews, New BrunswickSport climbing on basalt cliffs. Fun for a couple days and St-Andrews is beautiful in summer. A nice town to visit on the ocean. You can go out on a boat and see whales.
Dover Island, Nova ScotiaWorld class bouldering on granite near the crashing surf just off the coast of Peggy's Cove. Must park and take a small boat over to the island. You can plan a day trip or camp overnight. If you bring a tent I recommend camping one or two nights as this is one of the finest places on earth. Once on the island you can get around with your child carrier (backpack). Near the bouldering areas there is lots of flat ground for kids to play. The world renowned sea side town of Peggy's cove is very scenic and worth seeing.
Now that you have that info you should be able to do some internet searches for these areas. Also, check out the links button at the top of this site and you can find some valuable information. We'll be glad to answer any questions. Also, if you plan to climb in New Brunswick let me know and I'll try my best to get out and give you a tour.
Hope this helps.
cheers
Fred