One case I've always loved is the Fractal Design Define R4, simple and has some extra fan slots on the side and the roof whilst not having too much mesh and open holes but it's about the same size as a 500R.
On low settings (case fan controller) I can barely hear the system running and this is an a quiet place with no music or anything else running. Any talk, music etc. and I don't even notice it. I guess it's possible it's different with all your fans and a different controller. I did add some sound dampening foam as you can see in my signature but I'm not sure how much of a difference it made, it's like $3 worth of foam.
A silent case is definitely an option though, like the R4 you mentioned. What size is your motherboard? ATX or mATX? if it's mATX you have more options, if not that limits it a bit.