Ultimate Marvel was still..ultimately a recognizable version of the Marvel Universe just younger and somethings zigging where the regular 616 zagged (black Nick Fury, the Maker, lamer Galactus) but stuff like Spider-Man was still ultimately recognizable as the classic version of Spider-Man. So there's no need to go full 180 or "Stan Lee's version of DC" style elseworlds, so with that in mind.
-Diana is the Queen of Themyscira, Hippolyta passed away sometime ago.
-Diana and the Amazons first debuted in the world in WW2, and unlike the usual DC nonsense of "real world history isn't different despite supermen and gods fought in WW2". It's a full alternate history from 1941 onwards. The world is different, not a utopia but neither a dystopia. This opens up around an 80-90 year period where one can shove in WW stuff.
-She is a lesbian. Steve was still the first man who crashed on Themyscira but they didn't have a romantic relationship. He is an elderly WW2 vet by the time of the present, think the DCAU take.
-She has reformed villains as part of her supporting cast, an elderly Priscilla Rich being one of them.
-Etta Candy is a college student WW fangirl who worms her way into WW's life. Vanessa Kapatelis and Cassie Sandsmark are her friends/sorority sisters
-Stealing an idea from Rucka; Zeus and the original generation of Olympians were overthrown by the younger generation. Ares, Aphrodite, and Athena now rule but similar to Historia the Gods almost never appear in true physical form on Earth. They act through agents.
-Circe has been her pre-eminent enemy since coming to Man's World. Taking on a new identity every decade or so to oppose WW, be it as Paula Von FG in WW2, Lyta Milton in the 90s, Veronica Cale in the 2000s, etc
This is her outfit.