Nice choice. I had the same combo for my Space Gray iPhone 6S and Space Gray AW Sport. I just got a Space Gray iPad Pro 9.7 and got the silicone Midnight Blue case and Smart Cover as well.
Have to say, I was disappointed with the leather version of the Apple iPhone 6S case. For me, it got very slippery after about a month of use -- so slippery I was thinking of replacing it for fear of dropping my phone. It was also accumulating a darker coloring around the edges (some call this Patina). Anyway, I switched to the Midnight Blue silicone case, and it's been great. Much grippier, fits great, feels great, and wipes clean with a damp rag. For me, the silicone was a better choice.