About to start my OSX experiment and would like some suggestions

I've been in IT consulting for the last 7 years and I've seen quite a few companies switch to Mac over that time. I mostly work in the mobile space so I've become very familiar with iOS and have an iPad 3 and an iPhone 5. On the Mac side I've only ever used a Mac Mini regularly. That's my backstory.

Tomorrow I'll be receiving the 4GB/128GB Macbook Air (newest model) and outside of Chrome and a few others I know are multi-platform I'm not sure what apps I should be looking for. I'm fully entrenched in the Google ecosystem, so anything to plug into those email, contacts,docs, and calendars for multiple accounts would be great. Outside of that I rely pretty heavily on MetroTwit and OneNote.

Beyond that are there any apps you guys use which just has a standout experience to the utility of OSX?