After digging around the many spatial libraries available for working with SQL Spatial types offline in the Viking client I’ve settled on Microsoft.SqlServer.Types. The main advantage is the library supports the same functions I have available in SQL server. This is a big advantage in the UI when I can use STContains to do hit testing for arbitrarily complicated shapes. What I have not figured out is how to build a spatial index and easily render the CURVEDPOLYGON geometry.