There are a couple of examples hat come with LabVIEW that might help you. They can be found under Help >> Examples >> Advanced >> Picture Control >> "Polar Plot" and "Simple Smith Plot". As a way of comparing the two different plots, I had them plot the same data points. It looks like if you have a lot of data points with a lot variability then you want to use the Polar Plot. The following webpage may provide some infor regarding smith plots:
http://zone.ni.com/devzone/nidzgloss.nsf/webmain/80EC3CE5F229DB818625686A0078B8D9?OpenDocument