As I wrote before, Luke does take action in every novel series, but because they've written him into a corner by making him so powerful they have to be selective about when, where, and how to use him. Perhaps in a way they wouldn't with a less powerful Jedi like Jaina Solo, even though they underuse her despite her title as "Sword of the Jedi".
*****Warning: A little spoilerish regarding Bane novels*******
About the Bane books....my bad about the kids' names. I didn't remember that they used them first in Jedi v. Sith. I do think however that Bane was pretty unstoppable in the second Bane novel, due to the (hated) obelisks, but it is true that he was a newcomer in the first book and was just learning his powers and in the third book he was starting to slip a little, though he remained extremely powerful. So, yeah, the unstoppable force Bane is the one portrayed in the second book. Though I enjoyed the character's progression in all three books. I also liked Darth Zannah and wouldn't mind reading of her adventures.
Of course the problem with the pre-Sidious era Sith is that the writers are always going to have to find a way to keep their existence secret so the stories might run the risk of ending the same way, with the Sith tying up loose ends and remaining in the shadows. The 'heroes' won't be able to get the win. But since Zannah played such a significant role in the Bane books I wouldn't mind seeing her at least. Other than that, there's a Darth Plagueis book supposedly coming out. The Sith in between I can do without, though I am curious about Darth Vectivus (sp), who was introduced in Betrayal, the first LOTF novel.