Rocking chairs  

Heh -- there's a monster miter !  You can be sure that's splined . . .
 
Yes, scandesign, comfort is everything.  I've been militating for Wright houses that are open to visitors to have a reproduction dining and lounge chair (where the originals exist, on display) so that we can see for ourselves how they feel.

ScanDesign, she was fabulous. She was Garbo.

Leif, Now that is definitely not frumpy. The Kolds is beautiful. But like the Kayser, it is probably not a great rocker to sit in.
SDR, explain the spline. Do you use a router to add wood with the grain running the other way? I am just not sure what it is and how you put it in.
kate, I have a Porsche 911 cabriolet I nicknamed Garbo cuz she is also fabiulous. 

Scandesign, I have that Mogens Kold rocker and can confirm that it is quite comfy despite not having armrests. While the foam is thin, both seat and backrest utilize elastic webbing for the right amount of give.
 
It is usually the first chair that guests want to sit in.

 
That's a very special chair !
On a simple frame, for a window screen, say, the miters are glued and allowed to set. At any piont thereafter, the frame is stood on edge on the table saw and pushed part-way into the raised blade, creating a kerf.  Solid stock or plywood is prepared to match the thickness of the saw kerf, cut into right triangles with the grain parallel to the long edge of the triangle, the long edge is chamfered slightly, glue is spread on the triangle and on the edges of the saw cuts, and the triangle spline is pushed or tapped into place.  When the glue is dry, the excess spline is trimmed, perhaps with saw and router, or simply sanded.
The result is a visible spline. If this is not an acceptable feature, then the joint must be reinforced some other way -- perhaps with a concealed spline, or the joint made as a miter on one face and a half-lap on the other.
Earlier this year I made some large menu frames for a restaurant.  I used 1" Europly to make my   stiles and rails, at 3 1/12" width.  The mitered frames were too large to put on the saw as described above, so I cut the kerfs in the separate mitered stiles and rails, and inserted my splines (of 1/4" ply) during the glue-up, outdoors on horses.  Lots of fun -- but it went okay.

Today in the mail I received a Vatne chair by Fredrik Kayser.  It needs some cosmetic work, so it will be another project for me, in addition to all the other projects I have lined up. 
Having no arms, it does in fact make it much more difficult, if not impossible, for grandma to get in and out of this chair...but then this is not a chair meant for grandma.

Man, you have a big mailbox !
Yes, an armless rocker is a young person's chair, I suppose.  But that's a neato example . . . 

I think armless rockers were at one time called "sewing rockers" back when a lot of sewing was done by hand.  Or all sewing?  I guess arms would get in the way when arranging a big full skirted dress on one's lap to stitch seams and do hems...ugh.  I'm glad I was born later.