In STARLOG #85 interview to Richard Fleisher (dated 1984), he says that he is thinking about DARYL HANNAH to play the role of Sonja in the 1985 picture.
Hm, could have been better than Nielsen, I guess. Not the best actress ever but lightyears more talented than Nielsen...
Interestingly enough, Tarantino added a Fleisher's "RED SONJA" reference on his "Kill Bill vol. 2" during the fight between Thurman and Hannah fight. They both repeat a dialogue from the "Sonja" movie, so I wonder If Tarantino wasn't making a concious reference to the fact that Hannah was at some point going to star that old film... The "Kill Bill" movies also shared some other common points with the "Sonja" movie too, therefore the influence was clear.
Hannah had played the replicant-warrior woman on "Blade Runner" on 1982 and later the idiotic flick "Splash" were she showed her sweet ass with an annoying fishy smell
. After 1985 she would play the savage prehistoric Ayla in "Clan of the Cave Bear"
Also, even today she is both hot and tough. Fits with the Sonja character much better than McGowan (or Jessica Alba, by their asses' sake!!!). Sonja is not just a hottie with a sword, she is a proffesional assassin of men.
Sure, hot as hell. But brutal.
Is not that Hannah would be the perfect choice today, but is better than the current options.
Hannah even has some slightly "masculine" touches and a strong face, and still being beautiful.