Well I have used the Parting Glass on many the occasion. But now that I am getting into swing standards a bit, I am muchly taken by "We'll Meet Again".

...Don't know where, don't know when,
But I know we'll meet again some sunny day...

The trouble with these really good closing songs is that's about the only time you can play them, in any logical set-ordering scheme. So you have to choose one, it seems. Can't have them leaving all night. (Conversely, it you think your singing drives people away, you could play nothing but closing songs...now there's a thought that won't get you too many gigs.

Willie-O