If you can't decide...
The next step is to try them at home for at least a day each. Try the 11" first. If you love it, and don't mind the screen size, then you are done. Otherwise try the 13".
Why do it in that order? Chances are you are more familiar with what a larger size laptop feels like, but not the 11" MBA. Once you try the 11" MBA and decides that it works for you, there is less of a compelling reason to try a 13". On the other hand, if you try the 13", you will be second guessing what the 11" feels like.
That's exactly what I did. I originally wanted a 13" for its vertical resolution, but really wasn't sure whether the 11" screen would be fine, and I really like its form factor. After a day, I kept wishing there were more vertical screen space and realized that I didn't mind the MBA being larger. I switched to the 13" and it turned out to be the right size for me. In addition the larger screen and higher resolution, I actually prefer the larger MBA and I love the bigger trackpad. The extra battery life is a bonus.
The next step is to try them at home for at least a day each. Try the 11" first. If you love it, and don't mind the screen size, then you are done. Otherwise try the 13".
Why do it in that order? Chances are you are more familiar with what a larger size laptop feels like, but not the 11" MBA. Once you try the 11" MBA and decides that it works for you, there is less of a compelling reason to try a 13". On the other hand, if you try the 13", you will be second guessing what the 11" feels like.
That's exactly what I did. I originally wanted a 13" for its vertical resolution, but really wasn't sure whether the 11" screen would be fine, and I really like its form factor. After a day, I kept wishing there were more vertical screen space and realized that I didn't mind the MBA being larger. I switched to the 13" and it turned out to be the right size for me. In addition the larger screen and higher resolution, I actually prefer the larger MBA and I love the bigger trackpad. The extra battery life is a bonus.