The 13 inch form factor is just a deal breaker. It's the same foot print as any other 13 inch computer....why not just go for the Macbook Pro? A fully loaded 13 MBA is just too expensive for what it is. I do praise the 13 MBA for such a high resolution screen.
I went with the 11 because it's a revolutionary device. Look how similar it is to the 13 with such a smaller, sleeker form factor. A 13 MBA has been around for ages. Sure, benchmark points to dollars, the 13 will win hands down...but you sacrifice a bit of performance for a groundbreaking device in terms of size and capability with the 11.6.
That being said, I have an old (pre-unibody) 15 MBP I use at work and a desktop at home. I'd never consider either of the MBAs as primary machines....possibly the 13, but only if my work purchased it for me 🙂
If you really want dollar value, go for a 13 MBP