Over the weekend, I was on a flight from San Francisco to Philadelphia. I was using my iPad the entire time (using in-flight Gogo Wi-Fi) and at the end of the flight, I had over 65% of battery life. I was surprised at how much work I could get done by using an external Bluetooth keyboard.
When I travel in the future, I may end up leaving my laptop at home. I can access my Windows 7 PC remotely using LogMeIn Ignition and I can run a virtual machine of my Windows 7 computer. As I get more proficient at "pinch-to-zoom" and touch tapping, my efficiency on the iPad is definitely improving. Next: I will connect a Bluetooth mouse to my iPad so that I can replicate a true workstation experience.