St. Elmo's Fire is a generally forgettable movie, but foundational for the Brat Pack--the it new actors who ruled pop 1980s movies. The Lost Boys had the Coreys, Keifer Sutherland, and Diane Wiest, who was the iconic single, frazzled, 1980s mom. I still think the Brat Pack seals this matchup, but apparently you all disagree. Like many of these matchups, there's no doubt that the Lost Boys is a far superior movie.
Also "Santa Carla" (aka Santa Cruz) is close to where I grew up (and live), and a great setting for a vampire movie.