One of the most common questions I get from users is why can’t I choose a folder when I use File -> Save (As) and I have to tell them ‘click the little blue button with the black triangle.’ This expands the sheet (collapsed by default) to allow the user to choose a specific folder.
You can use this Terminal command to set this value (for all users):
defaults write /Library/Preferences/.GlobalPreferences NSNavPanelExpandedStateForSaveMode -string 1
defaults write ~/Library/Preferences/.GlobalPreferences NSNavPanelExpandedStateForSaveMode -string 1
for the currently logged in user.