According to Thierry Koblentz in Smashing Magazine’s article, “Device-Agnostic Approach To Responsive Web Design“, checking layouts against specific sets of dimensions is a losing battle.

I’m not a web developer though, and that’s not my battle (I’m glad too, that sounds like a tough fight).  I like to see how my site looks in other dimensions/devices. Thierry lists a number of responsive design test pages in his article, but I use a fast, convenient, and customizable extension for Chrome called Responsive Web Design Tester. It has many of the “standard” devices already installed, and allows users to add new devices and dimensions as needed.