Renzi worked her way up to unit manager and co-producer (with Jeffrey Nelson) on Sayles' 1982 gay-themed drama "Lianna", and worked without him for the first time in a small role in the Goldie Hawn vehicle "Swing Shift" (1984), directed by Jonathan Demme. She had a larger role in--and co-produced, with Peggy Rajski--Sayles' sci-fi adventure, "The Brother from Another Planet" (also 1984). She and Rajski co-produced Sayles' drama about a 1920s coal miner's strike, "Matewan" (1987). Rajski, Sayles and Renzi tried their hand on shorter forms in the mid-1980s, producing three successful Bruce Springsteen music videos, "Born in the USA", "I'm on Fire" and "Glory Days".
Back in features, Renzi acted in the 1988 baseball drama "Eight Men Out" (Rajski co-produced, and director Sayles also portrayed writer Ring Lardner). In 1990, she switched producing partners, teaming up with Sarah Green to form their own production company. Their first collaboration was "City of Hope" (1991), the Sayles-directed drama about Italian/Americans in New Jersey (Renzi also had a small role: "Never produce anything you don't act in", she bluntly laughed once). She, Green and Sayles filled their usual positions with "Passion Fish" (a 1992 drama about a paralyzed actress played by Mary McDonnell and her nurse portrayed by Alfre Woodard). She brought the idea for 1995's critically-acclaimed "The Secret of Roan Inish" to Sayles. Based on a novella by Rosalie K. Fry, it is a drama about an Irish girl and her interest in the Celtic legend of the half-human/half-seal Selkies. Renzi also produced "Lone Star" (1996), a Sayles-directed western mystery.