Did you try any of the XC trails? There is a simple trail that goes around the entire complex that is really suited to family runs. It has little if any elevation change. Shooting off of that are the singletrack trails. Climbing is involved but they can be rewarding as there are some pretty nice downhill sections with switchbacks.

The XC trails at Bromont offer little in terms of technical riding, though. They are pretty smooth with hardly any roots or rocks. There are some but not too much.