Does he spend a lot of time alone? How much exercise is he getting? Regardless of which methods you use, amping up his exercise is going to help. GSDs are high maintenance as far as time and attention and EXERCISE. Persistence and consistency are also necessary in redirecting/correcting unwanted behavior, and this means from all members of the household. This does not sound like a BAD dog, but one who needs LOTS of exercise and work to take the edge off his playfulness. Part of that exercise can be playing--with a soft frisbee, ball, tug... You also must exercise his brain as well as his body. These are the responsibilities of sharing your home with a smart, thinking canine. If she is willing, your wife should be a part of these things.