Just bought a 37" for the bedroom - it's a perfect size
I all honesty we found that our old 21" CRT picture was way too small for anything other than very occasional viewing.
Switching to widescreen meant picking a TV that has a screen of at least the same height or we'd of been effectively downsizing.
We sit about 1.8m from the screen which is just about right for standard-def on a 37". I'd of settled for a 32" at a push as I've tried that before but unless you're sitting no more than 1m from a 19" imho it'd be to small.