Your examples look good as they are. The 180mm will allow you to get further away and change the perspective.
Originally Posted by stradibarrius
As an experiment, you could take a shot similar to your first, then move the camera so the subject to lens distance doubles and take another shot.
If you crop and enlarge the second shot so the violin is the same size as the first, you should see the effect of the 180mm lens.
Obvious the 180mm lens will allow you to fill the frame from that position.