Hi Mia,
I love this song.  I didn't like it at first.  Joni Mitchell's stuff always seems to cram words into the music kind of awkwardly to my ear but if I listen closely and then listen again it becomes beautiful and unforgettable.  I didn't know she'd written it but after I found out I said to myself 'Of course.'
It's a thoughtful, personal musing on love or attachment.
'...still be on my feet...'  To me it means that too much of that person would not do you any harm.
I'll listen again and see if the meaning changes for me now that you've pointed it out.
And I'll read the lyrics to see if using my eyes changes it for me.

"Oh, I could drink a case of you darling 
Still I'd be on my feet 
I would still be on my feet"

I think the meaning of the chorus depends on which words are stressed. I would still be on my feet, or I would still be on my feet. The song seems to be talking about the bittersweet quality of a strong attachments (notice the duality throughout the song) Is Joni Mitchell pointing out her ability to continue to function through the "drunkenness" of such a strong attachment , stressing the word "still" -- or is she talking about the ability to still be herself after or during such a strong attachment, stressing the word "my"?

It's worth noting that the song refers to both Shakespeare and John Donne -- Shakespeare's "Let me not to the marriage of true minds admit impediments" and a variety of Donne poems concerning the mutual interpenetration of souls. 
And among her most Canadian songs (had to get that in).