I think being a tour guide might be perhaps a bit too, er, common for a member of the Royal family (and I say this having being a tour guide myself, at the U.S. Capitol. But I had that position because I was an unpaid intern and they tend to leave that stuff to the lowliest people on the staff, at least for small group tours). I realize there are all kinds of tour guides at different places (I've also been on a lot of tours), but it would seem a bit bizarre to me for a member of the Royal family to do that. I'm not sure Beatrice would think it a good idea, and I can only imagine what the press would say.
It would certainly be nice for Beatrice to find something to focus on, though. She's bright and educated and I'd think it'd be awfully boring to not have something on which she can focus, even if it's not a typical 9-to-5 job (which I don't really expect her to do, and, anyway, she has no need to). I'm sure there are plenty of areas in which there are opportunities for her, be it with charities, or within one of the palaces, or some other outside way to pursue an interest. And I say that less out of concern for how things appear to outsiders, but rather in hoping that she finds something fulfilling. Beatrice is about my age and most girls I know or know of go out and find a job or an interest of some kind, even if they're wealthy and/or planning to settle down and perhaps not pursue a career in the long term.