I don't use my MacBook Air that often, since I usually travel with a corporate behemoth and I'm otherwise home bound or occupied. So it's taken me a while to figure out how to make best use of the 11" screen. Here are some tips I've picked up:
- Apple made full screen mode for this device. Forget the stories about it being iOS-lite; you need full screen.
- Mountain Lion full screen works (Lion was awkward) thanks to the the 3 finger mission control gesture.
- You can move mission control screens around, so you can arrange the full screens in a common sequence that makes it easier to navigate them.
- Browser tabs now make sense. Each browser gets its own window (full screen), but tabs work within a screen. (There are some odd things with Chrome, full screen, and app switching, but not enough to make me displace Chrome as my full-time non-iOS browser).
- Sparrow for OS X is essential for a Gmail user, esp. now that Google's UIs waste vast amounts of screen real estate. Sadly it's in minimal maintenance mode (at best) since the team left for Google. It doesn't, for example, support Google two-factor verification; you have to use one of Google's security-annihilating not-really-application-specific passwords. I hope some other team will replicate Sparrow. If the Sparrow team/Google were honorable, they'd open source this app. $10 on the app store for ad-free, and worth it for however long it lasts. Since the data lives on Google there's no harm in using it for now. 
- I need something like Sparrow for Google Calendar -- we are cursed by Google's miserable space-wasting UI . I may try OS X Calendar.app again, too bad Fantastical isn't a native extension to Google Calendar (it works through iCal). BusyCal is $50; if it were $20 I'd try the free trial. 
 Mail.app IMAP syncs too much data locally, and Apple is incompetent at delivering net services like email and calendaring. I only need my full multi-GB email repository on my home server.
 Apple can't do net services, Google can't do UIs. Sigh.