When you are on the road a lot, there's simply no room to maneuver: you need a powerful laptop so that you can get things done. While the MacBook Air will do as a secondary machine, it won't be capable of doing everything. This is why we really like Daniel's setup and we hope to have a similar one in our home.
Daniel is a technician from Norway, and he likes his home setup pretty simple. We applaud the minimalism of this setup and the fact that it can be easily moved around, from workstation to workstation. While many people now use a laptop as their main computer, it's nice to have an external monitor, keyboard, and mouse to make working on your laptop easier. There are other add-ons that will make typing smoother, but they aren't required.
If your external keyboard is small enough, about the size of the Apple Bluetooth Keybord or smaller, you can easily carry it around with a Magic Mouse, an Apple Trackpad, or a Logitech laptop mouse. While it might seem counterintuitive, carrying the Apple Trackpad around is pretty nice because it will reposition the trackpad you are using to your left or right, depending if you're a leftie or a rightie, and that is a lot faster to use than a laptop's keyboard and trackpad, which is front-facing and problematic to use if you touch-type.
Daniel uses a 24" Apple LED Cinema Display as his external monitor. He uses Bowers & Wilkins P5 headphones, an Apple keyboard, and a wired Microsoft mouse. If it were our desk, we'd probably replace the mouse by a Bluetooth mouse. That would cut down on the wires but would consume a bit more power.
The overall footprint of this workstation is also very small, at around 30-35". This means that a desk like this can be set up as a secondary workstation in a home that needs it.
(Images with permission: Flickr member Daniel Elessedil Kjeserud)