I change cases for different uses, and for travel want extra protection. I have come to really like my BookBook case for travel. Has a couple advantages that come to mind:
1. Infinate viewing angle adjustment in landscape mode. Great for controlling glare.
2. When open, the outside of the coveris on the table (or airline tray). On some of my cases the inside of the cover would be on the table, picking up junk to transfer to the screen.
3. Really protective of the screen if you are putting it into a bag.
But yes, it does add bulk.