How do I get OS X 10.8.x to keep Finder windows open after a restart?
Try unchecking System Preferences > General > Close windows when quitting an application. 10.7 restored the state of applications by default but 10.8 doesn't.

This enables restoring state in just Finder:

defaults write com.apple.Finder NSQuitAlwaysKeepsWindows -bool true
killall Finder