I'm about to build a real desk to replace the Office Depot piece of crap that I have had for far too long now.

It will go in a corner, and I'm wondering how to make the corner part of the surface.

I can just miter the two parts of the L together, and join them with a spline.

What if I wanted a rounded inside corner - would you glue two "extensions" to the desk's surface so that they are joined at the same miter as the other two parts? I.e. the L is mitered as usual, and the inside curve is made from two symmetrical parts, again mitered together.

If I wanted to make my life hard and make the corner a third section (joined to the two sides of the L with two respective splines) - so as to make the grain "turn" less abruptly - would I need to miter it at 22.5 degrees to each side so that the wood's movement is equal between the corner piece and the side pieces?