I have switched recently to a MacBook Air. (I had offered to buy a new computer for my wife, but she doesn’t like new computers and preferred to take my MacBook Pro instead — I did, at least, outfit it with a new 128GB solid state drive before handing it over to her.) We have also purchased a Mac Mini to be the household computer, and it will also be where I do my downloading and cataloging of photographs from my fieldwork. The Mac Min will become, in essence, a production machine for me in addition to being a homework machine for our daughter — and perhaps, one day, a production machine for her.
I decided that I would not load up the MBA with all the software I had on the MBP. Photoshop and Illustrator, for example, just don’t work very well on a small machine I find. Luckily, for me, I have purchased both Acorn and Pixelmator in some of the bundles that various Mac software developers offer now and then. Even better, Pixelmator has a really nice collection of tutorials.