The APA merged with the Phoenix Theatre in 1964 and as the APA-Phoenix went on to mount Broadway revivals of Man and Superman, The Show Off, Right You Are If You Think You Are, and Hamlet (in which Rabb played the title role) among others, with the APA-Phoenix receiving a special Tony Award for distinguished achievement prior to disbanding in 1969.

His later directing work included a 1973 production of A Streetcar Named Desire, starring Rosemary Harris (to whom he was married from 1959 to 1967), James Farentino, and Patricia Conolly; a memorable all star Broadway revival of The Royal Family starring Rosemary Harris, Sam Levene, George Grizzard and Eva LeGalliene in 1975 for which he won both a Tony Award and a Drama Desk Award, and a 1983 revival of You Can't Take It with You with Jason Robards and Colleen Dewhurst.

Rabb's production of The Royal Family was filmed for the PBS series Great Performances on November 9, 1977;[1] this version was released on DVD.

Rabb replaced George Grizzard, who left due to prior commitments, in the role of Tony Cavendish in the Broadway revival of The Royal Family shortly after the revival opened and appeared in the PBS production as well.

He was unmasked as the former by Diane Chambers and as the latter by Coach, but was then found to be telling the truth when he claimed he was wealthy.