>When our boy, who's 14 months presents similar behavior to get us to play with him we say, "go get your toy" and try to redirect him to something that's ok to bark at, bite and jump on. Have we been causing him to form the wrong association?
Maybe. Think of the obnoxious behavior of a 3 year old hanging on his mother in the store. "Mom, mom mom mom mom mom mom!" And there you are, wishing she'd respond and shut him up and Mom is just totally oblivious until finally she says "What?"
That behavior probably started in their life when Mom didn't answer to "Mom!" Then Mom didn't answer to "Mom, mom!" Then Mom decided to try to wait out the obnoxious kid and didn't answer until the 5th "Mom!"
That's not teaching the kid to wait, it's teaching the kid that it may take 5 "Mom!"s or 10 "Mom!"s but eventually she'll answer if you just keep whining.
With your dog, I'd try to teach an acceptable behavior that indicates that the dog wants to play -- a behavior that you can acknowledge and respond to, or deny. For example, many have trained their dogs to go to some bells and ring them to go outside. You could train your dog to do something similar to initiate a wrestling/tug session. Try to initiate play before the dog does, and before you go get the toy, have the dog do something, like ring bells (if you don't already do that) or perhaps lie down by the toy box.
So when you want to play, take the dog to the toybox and put him on a down. Then say "wanna play?" and take out a toy and play. It's tedious at first, but eventually the dog's going to experiment and go lie down by the toybox, at which point you respons "Wanna play?" and immediately play.
You will have given the dog an appropriate way to request the activity. Now that doesn't mean you have to jump and play when the dog wants to (especially in the beginning, you have to do all the initiating and you will need to jump if the dog "gets it" or else you'll confuse him). However, later on, sometimes the dog will lie down (or do whatever behavior you planned) and you can say "no, go to bed" or call him to you for a sit and cuddle.
it gives the dog a way to request attention that's low key, and leaves the ball in your court as to whether to grant the request or not.