(I dont know why people dont take the whole case in the hotel room. That's beyond me... IT'S A CASE!)
Use whatever liner that came with the case. No need for a cute bag with straps nor anything.
I often only pack it half way, put it at the bottom as a damper, nd fold the rest as a divider in the upper part. It also limits free object shuffling.
For the rattling, you will always find a way to pack it pretty full, and if you spread the soft items like shirts, socks, rope, garbage bags, spare gloves, jacket liners, it's pretty steady.
Gravity helps and the top of the case is generally a large piece like the rainsuit or jacket liners, which limits the "jumping" aound in there.
For the small things, I pack a 5x5x5" or similar box, and fill the box's void with grocery bags, napkins or something equally useful.