light fixtures and hardware - can I mix metals?

I'm new here and am posting this before turning in. We're building house in a planned community. The house is a traditional style - 10 ft. ceilings, transoms over the doors, etc. The hardware on the windows and doors is nickel, and many of the light and plumbing fixtures are nickel as well. The living area and kitchen are open and I'm using a dark wood dining table. Can I use a darker metal light fixture over the breakfast bar and also over the dining table? I've made so many decisions my brain has declared mutiny. :-) Thanks in advance.