That’s my dilemma. I plan on jumping (T-Mobile JoD) to the X when those preorders go live, so I plan on getting a color different than the one I choose for the 8 plus. Probably the gold
If you go to the Apple site and look at the colors (as if you were going to buy one), it appears the backs are the color you choose, while the fronts are white except for the space gray, which is... space gray!