I can't say about the play being normal or not, but I do know that vibration in the 2000 + Bonneville'* is a very common problem. Ours has it also ( 2003 ) at about 65 - 75 MPH.
We have had people get their tires balanced two or three times and still have problems. It seems that some people have had luck with a road force balance, where the machine actually applies pressure via a roller to the tire during the balancing process.
Not sure if that helps, but might be worth looking into.