When looking for a breed of dog to suit your lifestyle, the size of the dog has nothing to do with the size of the yard, but the activity level of the dog. I would def want a big yard if I had a Lab, but the giant dogs pretty much sleep all day once they're mature. I have a 35 pound English Setter who is of the walls crazy, and a 140 pound Dane baby who seriously could live in a refridgerator box and be perfectly happy.
If you aren't going to have alot of room, I'd stay away from herding and hunting dogs, simply because they're so high maintenance. It will work though, if you put in the effort, like ectra time at the park or dog sports. Good luck!
Ang