I think what's really needed is the ability to set a default, and then for each phone number in a contact give the ability to force GV on or off. In an effort to best utilize minutes to everyone's benefit, I want to use GV when calling non-VZW numbers, and NOT use it when calling VZW numbers. There are also some exceptions that would apply, like numbers with an extended dialing sequence (i.e. calling voicemail, pausing, then entering a password).