That floating broom from Spirit is really cool. It looks like someone attached a broom to a Roomba. hah hah.

For the broom tie up, that's a neat idea. I wonder if you could attach brooms to it with say...metal half T's. I am not sure what they're called...the things that hold shelves up on walls, but smaller and just the T part, so you couldn't see them.

Looks like an L but sideways so you can attach the brooms. The you wouldn't have to mess with fishing line or anything.

On the other hand...my idea doesn't give the illusion of floating nearly as well as the fishing line thing does because the brooms would move around in that case, which would be neat.