I've not seen a responsive monitor like that. My Mac just has a fixed width monitor—about 65cm. I wouldn't really want it to stretch to 100% width of the room anyway. It would be a strain on my neck.
Originally Posted by felgall
It seems that monitors these days are heading more for the 16:9 aspect ratios (just an idea I have—sans evidence!), but I don't see that it matters much. I'd be looking more at a retina screen myself, whatever width and height, as the picture quality on those is amazing. (Not sure if anything but mobile Macs use them yet, though.)
@datadriven: The start of your question makes it sound like you are talking about buying a screen, while the end of your question makes it sound like you are asking about optimum website widths—hence the confusion, I think.