It would be great to have a drop down and select multiple devices then have a button to preview on all devices at once.
I'm constantly selected different devices when testing.
it would be nice but remember that several styles are recognizable only in a real tablet. Orientation, pixel size and so on.
I use http://helloduo.com ( via dropbox too)Responsive simulator online:The best: simulator 1simulator 2simulator 3simulator 4simulator 5