If you are looking for best/common practices and particular widths applied when using responsive layouts, I'd suggest you look into grid systems readily available. A quick google search yields a lot of results, but one of my favourite ones would be the 1140 grid from cssgrid.net (site no longer available) - I very much agree with their logic on choosing the measurements. Verbatim:
The 1140 grid fits perfectly into a 1280 monitor. On smaller monitors
it becomes fluid and adapts to the width of the browser.
Scrap 1024! Design once at 1140 for 1280, and with very little extra
work, it will adapt itself to work on just about any monitor, even
mobile.
If this is not the kind of answer you were looking for, please rephrase the question.
