Yeah, it totally depends on where you live, what you need, what you like, etc.. etc...
We're not getting rid of any
of our sheet music. Why? Hard to replace, hard to get a hold of, expensive, has to be in the right key/transposition, blah, blah, blah. And it's taking up more room than I wish it was.
I should also mention that I live 15 minutes by car from the University from which DH and I graduated. Their library is new, immense, and breathtaking. Their interlibrary loan system is even more jaw-dropping. I used to just try and find rare books through interlibrary loan just for the heck of it, and I learned that almost anything I ever wanted was available on there. So, I know that I can get a hold of practically any book I can possibly dream of.
That being said, we're still hanging on to plenty of books that we have decided are worth it to us to have around. That's what I mean by every family doing what works, you know? If we lived in the middle of nowhere and enjoyed reading super-rare stuff, then that would be a totally different situation. Do what works!
(God I wish there was a local appliance/equipment/power tool library!!