The trip jumped out at me.
If she is at all crafty or artsy, maybe a big scrapbook kit for the pictures of her trip. They make big kits geared towards travel, birthdays, baby,...etc.
One with lots of accessories that she and her friends could work on together after she comes back. She could make it into whatever she wanted.
Or, there are soooo many cool scrapbook/photo software kits for computers that allow you to do it all on a computer and share with friends.
Trip accessories, stylish travel purse/bag, camera storage, or tickets to somewhere very specific for a stop on her trip also come to mind.
Disclaimer: I don't have a 17 yro and am making blind suggestions here.