Q: Is there a way to change the view (cascade, horizontal or vertical tiling, side by side) when displaying 2 or more documents?

A:  Windows 7, Vista, and XP have native support for this function. For more information look at Tip #5 in Windows tricks.

Version 8 of PDF Studio added this ability for OS X and Linux/Unix as well.  There are options for Cascade, Tile, and Minimize All under the new Window menu.