There is no doubt that the DJI Phantom is one of the coolest gadgets out there, but sometimes you need to mix it up a little bit. For this, you need a rugged Travel Case! It has become one of my favorite extra items and one that I would consider essential. All of my fpv gear, batteries, chargers, and gopro all fit in here nicely and so far I have not had any issues when I have traveled. I did not even get strange looks from TSA when it went through the scanner. It has kept all my stuff in pristine condition when I went to Pacific Grove and on a family vacation to Bastrop State Park. I have a toddler, so you know this stuff gets banged around. Make sure you carry it on when you fly (don't check it) because they do not want batteries in the cargo hold.
The second best accessory for the Phantom is the EOS Sentry battery monitor. You just plug in the balancing plug of your battery and it tells you the voltage and estimates the amount of pack you have left. If you have more than one battery, you certainly can imagine how much time and frustration this saves you - you do not have to keep plugging batteries into the charger to check voltage etc. Maybe you are more organized than I am.. if not, then you should get one of these.