If you are getting a new Rose Gold iPhone 6S you are also probably looking for a new case to go with it.
Here is my recommendation Spigen [Ultra Hybrid] AIR CUSHION [Rose Crystal] Clear.
I am a big fan of Spigen cases as they are not only nicely made and minimalist but they are also reasonable priced.
I like this particularly model for the Rose Gold 6S as it matches perfectly.
And here are other Spigen cases for any 6S color.