From 1963 through 1983, Ross raised the company's profile through methods both grand and corny—including bumper stickers, skywriting, and advertisements in such unorthodox places as the sides of cement-mixers. He is best known for developing the company's regular productions of Wagner's Ring cycle, which premiered in 1975—when it was rare to see the four-opera cycle outside of Germany—and made Seattle Opera a destination for opera lovers all over the country.

Speight Jenkins, Ross's successor at Seattle Opera, said, "Everyone in the United States who loves opera owes a debt to Glynn. He showed that two communities who had only supported occasional touring opera could develop excellent regular opera companies."

Ross was also one of the creators of the Pacific Northwest Ballet (which was then affiliated with the opera company) and of Opera America, a national organization of opera companies.

Ross's tenure at the company ended in 1983, when he was forced, by the company's board, to retire. He went on to Arizona Opera, and worked similar magic there, building audiences and staging the Ring cycle. He retired from that company in 1998.