Searching the web gave me this terminal command:
defaults write -g NSNavPanelExpandedState ForSaveMode -bool TRUE
Entering it produces: Unexpected argument -bool; leaving defaults unchanged.
Changing TRUE to YES gave the same result.
It is supposed to set Save dialogs to the "long form", so you don't have to click the disclosure triangle to get a different view of possible locations in which to save.
While you're at it, how about a line that will do the same thing for Print dialogs. Something that defaults to the mode where the "Details" are not hidden in the dialog box.
Thank you one and all.
On a Mac since 1984.
Currently: 27" iMacs, Macbook Air, macOS 10.14.x,; iPhones, iPods and iPads galore!