[Tom Edgerton]

Richard Whitney has often said that the distance that most viewers will fall into almost automatically is about two to three times the vertical height of the painting, though this will vary with lighting, hanging position on the wall, and some other factors. It may be a good position to adopt while painting to make an overall evaluation at a given stage. I've tried to remember it just to jog me to step back often enough. The mirror thing is good also, in that it helps overcome limitations in a tiny studio, as viewing your work in a mirror behind you will automatically double the viewing distance.

Chris, maybe this speaks to your point about where a comfortable overall viewing distance is for most viewers.

Cheers...