If you're in Oakland County then, for the moment at least, 145.25 with a 100hz PL is a good choice. In the not too distant future we'll be switching to 146.90 since we currently have an interference problem with another system in Ohio on 145.25. You'll probably want to use the PL tone on the 145.25 frequency since there is a lot of cable TV interference on that frequency as well.
The switch to 146.90 was planned anyway, the interference from Ohio moved it up on the priority list.
Mike