I agree with everyone saying it's not the creative team, it's the editorial.

Diana needs dedicated editors, under her own office. Nothing else will matter until she's got some protection from management, and those editors enforce a level of consistency and world building the character has rarely ever had.

As far as creators go, a big long run from a quality talent will be a great starting point, but if the next creators afterwards are allowed to go their own way and reset everything then we won't be any better off than we are right now. So that editorial, and consistent, steady support, is critical.

Who was the Bat editor who left for Vertigo? Mark Doyle? That guy did a great job with the Bat books and the Vertigo stuff seemed quality while it lasted. So I'd see if I could set that guy up as Diana's editor.

As far as creators go, I think I'd like to lock Gaiman and Geoff Johns in a room for a weekend and make them write a character bible. Johns has a unnatural talent for working with continuity and Gaiman is.....well, he's Gaiman. Johns knows how to refine a character's mythos and Gaiman would be able to point things in the right direction, and between the two of them I think we could get a pretty fantastic foundation to build from.

Then I'd like to get Gaiman on the book for a minimum of two years. He can pick his artists himself.

But you know what? I'm not sure how much any effort would increase sales, at least in the short term. DC has spent years abusing Diana and letting writers churn out inconsistent product with no real, overall direction. And this has cultivated a sense among the general fandom that Diana's not worth reading. And they're right; what's the point in investing in the title when the next creators will just ignore all the development the previous guys did and go their own way? Years of inconsistency have done a lot of damage to Diana's brand and there's no quick, easy fix. It'll take long term investment to prove to readers that Diana's book is being treated better, and any big name creator or development is more than just a flash in the pan. DC should be looking for long-term, steady increases in sales instead of a quick, short-term spike.

Gaiman on WW would definitely do well in trade, but the direct market is too gun-shy about her book for any short-term effort to really provide any worthwhile gains. DC has to overcome the damage they've done to her before readers will trust that the book is worth keeping up with.