The most steamy and seductive sex scenes in Hollywood films are subjective and can vary depending on personal preferences. However, some scenes that have been widely regarded as hot and seductive include the library scene in Atonement, the dance scene in Dirty Dancing, and the road trip sex scenes in Y Tu Mamá También. Other notable mentions include the sex scenes in Eyes Wide Shut, 9 1/2 Weeks, Basic Instinct, and Blue is the Warmest Color. It's worth noting that while these scenes may be considered steamy and seductive, they may not be suitable for all audiences and viewer discretion is advised.