If you're talking about a wolf/dog mix, you've got to bear in mind that every single one is going to be different. You can't depend on looking at both sides of the mix to guage temperament, and there will always be that 'wild' streak in the dog. I see Bimmer literally switch gears sometimes, especially if he's hunting or if he perceives a threat.
Of all the mixes I've seen, the German Shepherds seem to be the most dependable. A good German Shepherd temperament seems to balance out better than something like a Malamute or Husky. Those strong instincts to herd and protect seem to work their magic.
A wolfdog isn't going to be terribly playful once it's past puppyhood unless it's caring for a puppy, so I really wouldn't suggest it as a playmate for a Boxer/Pit mix, as they tend to be playful their whole lives.
I really have mixed feelings about encouraging the breeding of these animals. There are cases where a knowledgeable, scientific breeder has actually approached interbreeding the wolf to dogs to create a breed with specific characteristics and to start 'clean' without so many of the genetic problems we've created in the overbred lines we have now, but by and large all these people are doing is breeding dogs that too often attract the wrong sort of owners and end up with sad, short lives.