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