Within the next 18 months I will be traveling out west to visit a few national parks as well as a trip to WDW. I`m currently using a Cannon 70D with a nice assortment of lenses. I have decided to buy a 6D in order to capture some of the beautiful lanscapes out west and to improve my dark-ride(low-light abilities) while at WDW. I was able capture some pretty good shots (dark rides) with the 70D and the Sigma 18-35 1.8 on my last trip but I`m hoping the 6D will do better. My question is: On a FF camera should I use a 50mm or a 35mm lens? ...or should I sell my 70D and lenses, forget the 6D and just buy the 5DmkIII?