I think in CoT, when Verin writes a letter to Rand saying that he can trust Cadsuane, but be wary of other sisters, she specifically calls out Elza as an example of one. Or maybe Rand thinks of her after reading the letter.

Of course, it could just be an example of Verin's plans going awry, ala her letter to Mat (possibly).

As for Elayne,confronting the Borderlanders specifically causes the unaligned houses to meet with her in the palace after she won the succession battle. That meeting nets her the last few houses she needs to be crowned.