I have a HD dust cover in the garage. It keeps the touchy stuff down and a waterproof one(no logo) for the road.Saved ME from getting soaked in a couple down pours. Let the bike take care of itself. I bought the cover.
Personally, I find that covers scratch the paint. Unless you totally dust it down, there is going to be fine scratches that will show up down the road. And if you don't wipe it down, the dirt from the bike or car will collect inside the cover and then it gets worse. Think about it.. there isn't any way for the dirt to not collect inside the cover.
If you want something for the seat to keep it cool or dry, try this arrangement.