My Ibanez guitar case smelled horrible, stale cigarettes......
I got a bunch of leaves (bay leaves I think), which were pretty fragrant, and stuck them in the case. Left it out open in the sun for a few days, and then closed it up with the leaves in.
As for the guitar, I put loads of lemon oil and fast fret on the fretboard, new strings, cleaned out the hardware. And just left it in my bedroom.