I got the gray smart cover but found the vinyl ones to be really cheap feeling so I've been wanting to try Black Leather. The problem is that people say they bleed and even Apple warns:
"*The leather Smart Cover is crafted from high-quality, naturally treated material that gets its color from a rich aniline dye. Some color may rub off during use."
So for now I use the Targus VuScape with a magnet taped on to replicate the "Instant-On" feature of the smart covers. (It's nice to know Apple didn't use proprietary magnets )