As a director, he was nominated for seven Tony Awards, winning three for his direction of I Love My Wife, Brighton Beach Memoirs and Biloxi Blues.

[5] On stage he also appeared in E. E. Cummings's Him,[6] A Shot in the Dark, The Tenth Man and A Thousand Clowns, in the role of Leo "Chuckles The Chipmunk" Herman, which he reprised in the film version.

He portrayed Jack Lemmon's brother in the screen adaptation of Simon's The Prisoner of Second Avenue, and also appeared in Nobody's Fool starring Paul Newman.

[7] Saks shared a long-term professional association with playwright/comedy writer Neil Simon,[8] directing Simon's plays Biloxi Blues, Brighton Beach Memoirs, Jake's Women, Rumors, Lost in Yonkers, Broadway Bound, The Odd Couple (1985 revival with female cast) and California Suite.

Among Saks's film directing credits were Barefoot in the Park, The Odd Couple, Cactus Flower (which won Goldie Hawn the Academy Award for Best Supporting Actress), Last of the Red Hot Lovers, Mame, Brighton Beach Memoirs, A Fine Romance, and the 1995 television production of Bye Bye Birdie.