Since a lot of 18th-century opera (at least until Mozart started putting real people on the stage) is so highly stylized, and since the staging of an opera based on Greek myth could hardly be naturalistic anyway, directors have a lot of leeway. Seattle Operas fall presentation, a co-production with the Metropolitan Opera, is Glucks Iphigenia in Tauris, his 1779 tale of a priestess ordered to sacrifice two enemy captives to the gods without realizing theyrewell, wait and find out. San Franciscos production in June, a friend reports, was all in black, with a black floor and walls with words and outlined images drawn on them in chalk. From the sketches Seattle Opera provided, it looks like Thomas Lynchs set is going for imposing Bronze-Age gloom. Stephen Wadsworth, whose credits for Seattle Opera include the lavishly sylvan Ring and an English-country-house Xerxes, will direct.