In the editor, I set my tab bar's position to the "Left".
I set "Multi-line Tabs" to true.
These settings stick when I close and reopen Toad.
I also set the "Rotate" setting to true to keep the tabs on the left but vertically stacked for maximum code window vertical space.
But the Rotate setting never sticks between runs of Toad.
Waiting for fix in a future version of Toad for Oracle.