Choose WindowDisplay > Toggles > Model
.
When the wireframe is hidden you can only see shaded surfaces.
Choose WindowDisplay > Anti-Alias > Wireframe Anti-Alias.
Set the Wireframe Anti-Alias options for your model.
Anti-aliasing produces a higher quality screen image, but it does not affect the quality of the model being displayed. It can also slow redraws significantly depending on the machine you are using.