Since I use Calibre heavily on my desktop pc, which I use daily, I find 8 Gb to be plenty. I load up hundreds of books at a time on my clara (8gb) and it barely puts a dent on it. If I didn't have so much opportunity to load books from my PC I'd probably go for the 32 gb. (I was considering it for a while, but I just got a new PC with a TB of storage, so I think I'm good to go.)
