If she's just decided she wants to get a tattoo while she is someplace without really having a reason for doing it in that place (a particular artist) then I would be concerned that not enough thought has gone into getting it.
There's nothing magical about tattoos received in Los Angeles. Where she goes should be informed by both personal recommendations and what kind of tattoo is being sought (if it is just flash that can be done anywhere, talk her out of it). If it is a complex piece I'd generally recommend Pat Fish up in Santa Barbara (not knowing style it is really hard to be specific; Pat does great work generally but is fantastic with Celtic designs), but if San Diego is too far, so is Santa Barbara.
So I guess the first question is does she know what she wants?
I asked Lani and all of the people she'd recommend are not the kind you just walk in on (several month waiting lists) and are definitely not the destination for flash.
Lani used to be the primary maintainer of the comprehensive
rec.arts.bodyart FAQ. With the decline of USENET it isn't much maintained anymore but most of the fundamental information is still accurate and the
Artists section is still maintained. That includes reviews from the rec.arts.bodyart newsgroup of various artists around the country including some in L.A.