How do I build a diagramming application in .NET?

I want to write a GUI seating application that allows users to draw and annotate simple "maps" of seating areas.

The end result would probably look something a little like Visio, but specifically for manipulating my "seating" data model rather than producing files.

In Java-land, there's the Graphical Editing Framework (GEF) -- is there anything like this in the .NET space? Should I just use System.Drawing.Drawing2D primitives and handle it all myself?

Solution

Here is product from Nevron. It is paid but doing it all yourself will take lot of time and effort.

Open Diagram and EasyDiagram.net are available at Codeplex. Be sure to download and look into their code.