Set print layout as default view in Word 2013
If you want to keep Protected View enabled but still disable Reading View as default, go to File > Options > General > Uncheck Open e-mail attachments and other uneditable files in reading view.
This is safer than disabling Protected View altogether.
(Thanks to folks in the comments for pointing out the above.)
You can go further and turn off Protected View for downloaded files by going to
File > Options > Trust Center > Trust Center Settings... > Protected View > Uncheck Enable Protected View for files originating from the Internet. You may want to uncheck the other two boxes while you're there.
(This applies in Word 2010 as well.)
After that, editable files will open normally and in Print Layout. No need to also turn off Reading View specifically if you go this route, at least in Word 2013 Preview.
Keep in mind that this will do away with the protection from malicious scripting that may be hidden in untrusted documents you've downloaded. If you're worried about that, you should probably just disable opening in Reading View as described in the first part above and leave Protected View enabled.
Something to try:
Check out File -> Options -> General tab- > Un-check "Open e-mail attachments and other uneditable files in reading view".