re: How to leverage new job offer for raise/benefits at current job?

There's a Wall Street Journal statistic out there that 93% of people who accept counter offers are gone within 18 months. You can Google that and figure out that maybe it's not a great idea to consider taking a counter. Of the 7% remaining some percent of that are still always looking. Which is true of me, I always keep an eye open for that big break.

At some point you might just need to consider that her current company is just a bad culture situation and she'll never really flourish there.