I went 256GB for the 2013, and had 256 in my last Air. It might get tight if you want to run a big bootcamp partition, or want to edit HD video - but if not you'll be fine. I plan on getting a external HDD for archiving files I dont often use but dont want to delete.
One can buy a 4TB external drive today for $150. So one has to ask oneself... Do u REALLY need all that space with u at all times?
For those who thought 256gb was not enough and opted for the 512gb, what do you use it for? I am still leaning towards 256gb, but I fear I may need more space in the future.
Also, as a main laptop, would 512gb be recommended? So hard to justify the ~$290(between the i7/8/256gb and i7/8/512gb after tax even with student discount) for 256gb more. Maybe if the back to school promo discount turns out to be like a $100 gift card, then I will consider getting the 512gb.