This sounds very exciting but very tricky from the musical side, because there are no male characters in Bernarda Alba; instead there's Bernarda, her mother, the servant Poncia, and Bernarda's 5 daughters, plus a few smaller walk-ons for other female characters. I suspect it's going to be a real challenge for LaChiusa to write for 8 or more women's voices in solos and ensembles and differentiate them musically -- sometimes in stagings of Lorca's play it can be a bit difficult at first to tell the 5 sisters apart, especially since they're all dressed in mourning.
I'm guessing Rubin-Vega is going to be playing Adela, the youngest daughter -- who has an affair with her (half)-sister's fiance and ends up hanging herself at the end. The CHOICE role, of course, is Bernarda herself, the matriarch who rules with an iron hand -- in the play she's supposed to be 60, so this will be a great part for an actress old enough to be convincing as the mother of 5 grown daughters in their 20s and 30s.
"Sweet summer evenings, hot wine and bread /
Sharing your supper, sharing your bed /
Simple joys have a simple voice:
It says why not go ahead?"