Anyone find a decent case or back cover that doesn't completely defeat the excellent weight and size of the iPad Air? I'm currently using the Smart Cover on the front. Not as good as my old leather version, but it's light. I would like to protect the back and corners. I tried the invellop case. It's nice and not much $$ but adds way too much bulk to the design. My iPad Air suddenly felt heavier than my old ipad 3. Trying not to play the buy and return game with Amazon. Can anyone recommend a decent slim case or back cover?