Check out the maintained nature trails in your area. They make a great change in routine, and they can be a lot of fun! Take the dog, the kids, the spouse, maybe even the in-laws, if they are likely to get lost enroute.... :D
When I take my dog, I try to take a new trail every time, which challenges both my sense of direction and my fitness level. As an added bonus, Cooper is completely engaged during the walk, and completely exhausted at the end!