I have Win8.1 Enterprise, running under Parallels on OSX.
Parallels installs the "English (Apple) - Parallels" keyboard layout. Because I have a non-Apple USB keyboard I (in the past, in Win 8.1. Pro) have installed the standard English layout and used SHIFT+WIN+SPACE shortcut to switch between input types (which is just a shortcut for clicking the language bar and making a selection).
However, on this install, the only way to get the language bar to appear is if I add a whole new language (e.g. Afrikaans, which I don't speak). Even then, the language bar only allows me to choose between languages, not keyboard layouts.
I've compare the Control Panel->Languages settings between a working machine and this new one and find them to be identical.
Is it a bug/change for the Enterprise edition, perhaps?
UPDATE: I've discovered this isn't a Pro vs. Enterprise problem. Seems it's just something about 8.1. Oh well.