Don't forget the OS takes up some space too, I don't know how much but if it's saying 213MB free then I'd believe it.
But, of the supposed 16 GB the machine came with, how much is taken up by the OS? I assumed the 11.9 GB quoted is what's left over when the OS has been installed.
Maybe most of your photos (and music, videos, etc) are on iCloud and not local? If you can move the local stuff to the cloud and live with needing an internet connection to get them that would prolly help.
By 'local', do you mean actually on the iPad? We've never used iCloud. All of the photos, videos and music are on our iMac, having been transferred there.
I noticed I could live without a bunch of apps on my device, so you might delete un-used apps. You can always re-install them later as you've paid for them.
We've done a bit of that. Might look some more.
Thanks for your reply, btw, azrich.