By holding the “Windows” key on a Microsoft keyboard, in Ubuntu, you get a MacOS-like view where you can move apps across workspaces; this is a super-useful features (and complements well the Shift-Alt-Up/Down combination to move windows across workspaces), however it does miss the ability to also move workspaces around.

There is an excellent extension to do this (Reorder Workspaces), and it works flawlessly by using the Alt-up/down key when in the workspaces-view mode: