in the keg, I only use leaf hops, never pellets. And I either go into a nylon bag, or let the swim free, with a sure screen. I've used a muslin bag, and i've used pellets, but I think the whole idea is to get the oils into your beer while keeping out vegative matter. Sometimes I'll use both a nylon bag and a sure screen.
I have never had the need to suspend the bag in anyway so it didn't reach the bottom. Hops float ya know! I've never had a clog nor a situation where the dry hops went grassy after too much time.