You might search by diva instead of by opera. All the greats have compilation albums that will feature some of the most impressive arias from the canon.
-Maria Callas
-Elizabeth Schwarzkopf
-Marilyn Horne
-Renee Fleming
-Cecilia Bartoli
-Countless others
You might also go for some Schubert or Schumann lieder. Not the uber-Romantic Wagnerian fat lady stuff at all (indeed, not opera), but absolutely gorgeous nonetheless. Kathleen Battle has a wonderful voice (and a serious 'tude)
-Maria Callas
-Elizabeth Schwarzkopf
-Marilyn Horne
-Renee Fleming
-Cecilia Bartoli
-Countless others
You might also go for some Schubert or Schumann lieder. Not the uber-Romantic Wagnerian fat lady stuff at all (indeed, not opera), but absolutely gorgeous nonetheless. Kathleen Battle has a wonderful voice (and a serious 'tude)