I got the 32G version and if I didn't want to put movies and music on it, then it would be a waste of money. I have a good number of apps and a few games. Right now I have about 11G free, but that's because I have several movies (they wind up being about 1+ gig each after I convert them, but then I don't use all that high a resolution) that I haven't bothered to delete.
I think the 16G version would be fine (I wanted the cell version of the N7 and it only came with 32GB) but I suspect the 8 is too little.
By the way, as to those people who will tell you that you can just add a USB drive if you need more storage: Yes, you can if you root your device and if you want to live with something dangling off the bottom. Rooting isn't a huge deal, but not everyone wants to do that.