I have heard those silcone type covers can be hard to get it on and they trap dirt and get a little nasty. You might want to try a skin, they look great and will protect your K from getting dirty. Then a good cover to protect even further and make it easy to read.
I have heard good things about the M edge as mentioned above but I have
this one which comes with a light. It is slim and light weight and l like it a lot but just switched to an Oberon which was a gift and is pretty amazing but pricey.
There are several post already on this board on skins and covers... look through and I am sure you will be able to choose what you need.