You may have a bit of a problem getting much in the way of responses on this thread. Female snowboarders are a minority and female snowboarders that are heavily enough into park to have a park board/bindings probably even more so.
Maybe a better question would be what to avoid for park bindings? You've already identified rear-entry bindings. I have some Rome 390s on my park board, but I don't do enough park for it to make much difference whether I had Romes or Unions or whatnot. How much precision do you need? Are you looking for the best women's binding for park, or are you just looking to avoid making a show-stopper mistake?
Illegitimi non carborundum
I hate the parts between winter...