Congratulations to your niece - that's quite an accomplishment!
Invitations to graduation parties are starting to pile up on my desk, too. I guess what I give depends on how close I am to the graduate. I've often given money, but I know that's not very personal (but always appreciated). Sometimes I've given money and a small personal gift such as an engraved keyring or a piece of jewelry. When the graduate is someone very close, I've sometimes put together a small memory/photo album with pictures I've taken over the years that they didn't have. That always goes over very well. I've also given books that I've found meaningful (and that I know the graduate would appreciate,too). I have a friend that always puts together a kind of "college survival" gift basket for graduates.
I wonder if there are regional differences in common gift choices. Does your niece have an "official" list like a registry? I'm not familiar with that for graduations. Or is it just an informal wish list that you know about? I do like your idea of a gift she could keep forever.
Marie