Zumocast has two of my PCs' entire libraries shared. It works great.
I have little desire to maintain a large amount of "stuff" on my iPad when it also lives elsewhere and is readily accessible. Seems a waste and to me to care and feed yet another device. And even 64 GB is not "enough" if I truly did want it all so I see no need to compromise and have to pick and choose what gets loaded--only to have that need constant changing to stay current.
Besides apps, the only thing I will load on-board is a movie or some other video if I know I will be out of range (like flying without WiFi). Music wise I only sync my current favorites since I keep that updated in iTunes anyway. Oh I keep books but they take up little space.
As of right now I have a whopping 7GB on my iPad and that could be trimmed to 5 if I got rid of apps I never use. I could get by with an 8GB iPad, though I wouldn't want to go that low lol.