[Avodah] Season's Greetings

[Simon Wanderer]

Anyone have any thoughts / sources on G'mar Tov Vs G'mar Chasima Tova (vis a vis origin, meaning and correctness)? I would have expected this to be well-trodden ground on the internet, but a quick google search did not turn anything up. 

Whilst on the subject, what about the correct greeting for Motzei Yom Kippur? Since last night I have heard (all from people I do not think of as ignorant):
Gut Yom Tov;
Gut Yohr; and
G'mar Tov

Again, any thoughts or sources?

Thanks,

-- SW