You can create an app which has the correct ratio (width - heigth) for use on every device.
When you take the smallest one, it will be fine for the bigger resolutions.
An iPad will auto shrink it, if needed (or turn your iPad from landscape to portrait and back)
I now use this as standard resolution : 1280 x 800
If you use it on AccessPoint and press F11 in IE, you see everything.
On iPad it just works fine for the user, and new desktop / laptops have higher resolutions than this.
The 'old' standard of 1024 x 768 is just old
You could resize your window when developing : View - Resize window - 1280x800