Money is the other extreme, it says "I really have no idea what kind of gift you'd like", so apparently you hardly know each other.
Gift cards are at least a small step up, you show you think the other likes to travel.
On the one hand, giving a well-received physical gift shows that you know the person enough to get them something they wanted. On the other hand, it also risks they'll have an unplanned item that kind-of-but-not-quite matches what they actually wanted, creating friction and inconvenience in their lives. I know this is a custom, but personally, I'd much prefer to get a monetary equivalent instead.
(One custom in my area I know where giving actual money is still expected is weddings. This is usually justified by the fact that organizing a wedding costs a ton of money, so this helps the newlyweds recoup the expense.)
I should give her a call.