Here are some iPhone travel tips.
1. Don’t bother getting an airplane charger or car charger. It’s still rare that airplanes will have the power outlets, and if they do, it’s probably not going to be at your seat. Instead, get one of those lithium battery packs. They charge from a USB socket and have one of their own to charge an iPhone or anything else that can use it. I’ll edit this post when I get home to link to the one I use. You can get various capacities.
2. If you want to listen music in your hotel room, and didn’t bring any speakers and your hotel room doesn’t have any, just put your iPhone into the trash bin and adjust the volume as desired. The trash can will act as a megaphone and amplify your music.
3. If you like to watch movies on the plane, it can be tiring to hold up your device on long flights. Luckily, you can build a cheap and easy holder. Get a large binder clip and a metal wire hanger. Take one of the handles off the binder clip. Cut and bend the hanger into a complex U shape such that it has tabs that will fit into the clip and a small shelf upon which you can rest your device. I’ll edit this post later and add a better description and photos. 
4. Here’s an interesting article about international travelling with your iPhone. It discusses how to best use ATT’s international roaming plans.