Personal Hotspot is Better Over Bluetooth
If you've got an iPhone and your carrier allows it (or you've paid the extra in the US to use it), Personal Hotspot is one of the best features in the iPhone (or Android phone that supports tethering). Turn it on, and within seconds you can be browsing on your laptop or Wifi-only iPad. I used to have a data plan on a 3G USB adapter so I could work on the go with my MacBook regardless of whether the place I was working had Wifi, but ever since I got my iPhone, I've used its Personal Hotspot instead. It's simple, gets comparatively great speeds, and gives me one less thing to keep up with.
There's only one problem: sharing the internet connection over Wifi goes through your battery rather fast. It's still not that bad, but it'll easily eat 50% of your battery in a 2-3hr session. Tethering over USB alleviates that problem, at least for your iPhone, but it means you've got a cable to remember to bring and keep up with.
There's another solution that I never even thought to try until today: Bluetooth tethering. It sounds archaic and slow, but actually worked out better. And it wasn't slow, either: the speeds were essentially the same as I typically get through 3G already, or around 1.5Mb down and 1Mb up. Comically, it was faster to connect. I always seem to have a somewhat tricky time getting my iPhone's Wifi hotspot to show up in areas with tons of Wifi networks, but connecting via Bluetooth literally took two seconds. You pair your phone with your laptop, if you haven't already, then click the gear icon in your Bluetooth settings and select Connect to Network. Put your laptop to sleep and wake it up, and repeat those steps, and — no joke — it'll connect the entire way in 2 seconds.
That's faster and simpler than connection to my iPhone's internet over Wifi, and it was definitely easier on my MacBook Air and iPhone's battery life.
So there's you a little mobility tip to try out.
Thoughts? @reply me on Twitter.