Scissor switches can be quite comfortable, and the macbook air has quite nice switches (IMO I like the thinkpad x1 carbon's a little better, but it is close), and the location of the trackpad being under the keys is much more comfortable than having a physical mouse to the left or right.

For my desktop I have a kinesis advantage, but I often find using my thinkpad for long periods of time to be very comfortable, I just wish I could find a decent trackpad for my desktop(s).