For the 64GB - 11" MBA, how much free space do you start out with?
No one at the apple store seemed to know unfortunately, and all the demos are loaded up with extra content.
On a side note, the one difference I noticed between the 11" and 13" versions not mentioned yet, is the speakers are definitely more powerful on the 13". The 11" is certainly loud enough, but you have to pump it to close to max volume. The 13" version, 'loud enough' is the usual midrange on the selector.