Before I say anything else, I'd better come clean: in my native speech, it's common to say "her" for "she", and I still do it when I'm off duty as an Upholder of English Grammar. But(!) "for you and I" really gets up my nose -- in a modern non-dialect song, there's no excuse except ignorance. The clouds might roll by for you, but they most certainly don't for I!

Having said that, there are occasions where dialect or rusticity or whatever it was that applied when the song was created (I'm back to "proper" Folk songs now) that make it OK. And I'm perfectly happy to sing "they're playing for you and I" in Colum Sand's "Buskers" since I met the man and he explained that getting the right effect is more important than getting the right grammar.

Conclusion: it's not OK, but it's OK.

Double negatives are a bit different. It's the norm in French, for instance, to say "je ne sais rien" -- "I don't know nothing". And if it was good enough for Shakespeare (I forget what the example was!) it's certainly good enough for me!

Steve