This is all just my personal opinion...I don't think there are any "rules" for this per se. We custom built our home, and I felt like the door hinges and knobs should be consistent throughout our house, but I do not think that it is important that the plumbing fixtures and cabinetry hardware match the door hardware. I also think there is nothing wrong with using different finishes in different rooms...I used antique nickel fixtures in my powder room, brushed nickel in my master bath, a stainless steel faucet and sink in kitchen with nickel cabinet hardware. My door knobs and hinges are ORB (which reads black to me) throughout and everything looks fine together.

I also think antique brass looks lovely and timeless. Really, I think it is hard to go wrong with this.

Trend, as far as I can judge, is gold, copper, and flat black. Of course other finishes are widely used by most. But I wouldn't worry about trends so much. What I would worry about-is how my chosen finish going to look like. For example chrome or nickel look good both in cheaper options and in more expensive ones. Brass or gold or oil-rubbed bronze can be extremely beautiful, but then they would cost more. And if they are cheap they sometimes won't look that great.

I think some level of mixing finishes is perfectly acceptable, and can ever be extremely beautiful at times, but requires confidence and good eye. But if for example you are going with dark levers, black or bronze, and the hardware in bath is pewter or nickel-I think it will work. If levers are black and hardware is brass-would also work. Now, mixing "silver" finishes and gold ones-here I'd be more careful, because that's much harder to pull off.

My preferred finishes are copper, polished nickel, antique silver, antique brass, pewter..all of these usually require special order and longer lead time, just something to keep in mind. I went with polished nickel in master bath-frankly, if I knew it'd be such a pain, I'd reconsider.

As for the contrast-I think bronze or black would look amazing with white doors. Unless you have doors that you dislike so much you'd rather unsee them..:)

I hope to see other answers here too, choosing hardware is an interesting topic.

Thank you all for your comments. Still haven't made up my mind but leaning towards flat black hinges and door levers with pewter bathroom fixtures in part of the bathrooms and either flat black or bronze in the other bathroom. Since the French door hardware is already a deep bronze, almost black, I think that combination with work well.