id normally say plain for the office but i really dont follow that rule at my current job. i think medallions are more fun, and the male population at my office thinks that steve madden slip on square toed elf shoes are the bomb. Now i just wear whatever i feel like.
i love reading this exact same topic posted what seems to be on a weekly basis. If a black shirt makes your GF happy which in turn will get you laid, then wear the black shirt. Most likely nobody there will even know the difference nor will they care.