I've always considered the 15" Mac laptops to be the sweet spot in the lineup. It's all about personal preferences and the compromises between portability vs. usability. One thing that has me totally smitten with my MBA is the insanely great battery life. I originally went to my local Apple Store with the certainty I was walking out with the 11" MBA. However, after using both in the store, I walked out pleased as punch with the 13" model. It's awesome for my uses. I'm the Recording Secretary for our lake association and my MBA picks up my Wi-Fi signal from across our small lake! As long as I'm line-of-sight with my house I get a strong signal from my home network at a range of maybe 250-300 meters with my AirPort Extreme Base Station (the tall tower model). But I do hunger for that additional screen real estate a 15" model would give me. Anybody else thing a 15" MacBook Air would be a spiffing addition to the lineup? Of course I'm assuming the bigger screen wouldn't kill the battery life that's so important. But perhaps a *slightly* larger battery could be used. The weight penalty for stretching the battery wouldn't be that great going from a 13" case to a 15" case. I'd be shocked if it added even a 1/4 pound, and even that would be acceptable to me.