I personally would want more connection between the kitchen and pantry, but the powder room is fair game. All individual rooms don't have to have matching metal finishes. And all rooms don't have to have only one metal finish. For example, in my kitchen I have both bronze and copper. In my living room, I have matte brass and bronze. But, if you're going to change cabinet color between kitchen and pantry, I feel like you'd want to have the metals in both spaces be more similar so they have something in common. Hope that makes sense.

I like the combinations you are talking about, but have to agree that while navy with brass would be handsome, it might or might not be right for a pantry -- depends largely on how connected it is to your kitchen versus how much it stands on its own. Will the cabinets be the same or different styles? Navy also looks great with brushed nickel or satin chrome. The white and gray could look great with brass too. But if you really want those finishes and the rooms are somewhat open to each other, look for a way to tie them together -- or stand apart.