I couldn't make up my mind. Ended up buying the 13 initially...The i5/4/256. With the intention of returning it if I still desired the 11 (I bought my wife the 11" 2010 Ultimate last year).
Long story short...I love the 13, kept it...and also bought an 11" (2011) ultimate (core i7, 4g, 256g)...now we have both, including last year's 11". We've decided to use the 11s as our field back up computers to our iMacs. We run an A/V production business...but in Alaska, our mainstay over the summertime is weddings...we DJ them, uplighting, videography, etc. We use 21.5" iMacs as our primary machines...but redundancy is necessary. Up until now, we've used 15 or 17" MBPs. Now...it's the Airs. With external back up hard drives for our music and video libraries. I am absolutely in LOVE with these new Airs. They are easily my favorite computer Apple has ever built...and the 11" Air takes the cake. While I do own both...wherever I got, I've got a really cool "Murse" (Man Purse) that carries both my 11" Air and my iPad2. I don't go anywhere without both
I'm kind of worried about myself. I can't stop buying the new Mac products and justifying their purchases with something to do with our business

Oh Well! We've done 93 weddings this summer, 14 class reunions, and a dozen birthday parties...so we're doing OK in our booking department...and with the two Macs on site, I NEVER have to carry CDs with me any longer! As well...with the iPhone tethering, I'm online all the time...and if that obscure track comes up, or the most recent youtube tune is requested, we've got it within 30-45 seconds! As well, AT&T just turned their "4g" network on here...so I picked up one of their 4g cards this past week. UnBelievable!!! I'm getting 7-10 mb/s down and up to 4mb/s UP!!! I can D/L an iTunes track in less than 10 seconds
That's probably the ONLY request I would like to make in future builds of the Air. A universal 3/4g radio for the ability to be online anytime!!!
Jer