Atmel Studio 6 Simulator Not Showing Up
Be sure atfw.exe runs without problems (found in C:\Program Files (x86)\Atmel\Atmel Studio 6.2\atbackend). I found atfw.exe was missing wdapi1010.dll.

Copy wdapi1010.dll from C:\Program Files (x86)\Atmel\Atmel USB Drivers\Jungo\usb64 to the atfw.exe directory. Now simulator and programmer are avail in Atmel Studio 6.2.