my own view is that it depends on who gets the camera.
the K10D and K200D are using essentually the same sensor, so except for camera features,
AND SIZEthere is not much difference.
The K20 and K10 are in the same body but the K20 has the 14mp cmoss sensor, and woud be better at high ISO.
If you are going to use it, then a K20 might be the way to go, your wife can have your K200, you will have no problem helping to explain the controls because you use it, and you get the new toy to figure out.
If you don;t like the size etc, then as someone suggested look for a used KX.
In the long run, you could justify all the way up to a brand new K7 if you want because you can always share lenses
explain this to your wife, as she will have to buy her own lenses making it much more expensive for the two of you as a couple