Spouse and I tried out the new Toronto trail along the Finch hydro corridor today, and it's quite fun. Eventually they plan a complete ring of trails around the city from the Humber to Scarborough -- I'm guessing it will be 80km or more when it's done, although there's a ways to go. It was pretty empty except for one very, very evil spot just by Bathurst with every family in North York ambling across the trail on their way to a soccer game -- they really needed to think that area through a little better. The people there are just not thinking bikes, and the designers put the trail between access/parking area and soccer pitches, so there is bound to be trouble. (You can avoid that bit by heading north a block and taking the road parallel to the cemetary).
The sad thing is that the trail doesn't connect anything with anything yet. We started at Finch subway and ended when the trail ended maybe 10 km down the road, and all that was left was meandering up through a few parks and heading back through residential streets. We rode 25km in total, which is better than not riding at all.
Now I admit I'll take country roads over bike trails at any time, and I'll take quiet city roads over trails most of the time. But it's certainly a project worth encouraging, and a nice little trail to ride.