With visions of “Fantastic Four’s” $56 million opening weekend in their heads, Hollywood execs and talent are heading to San Diego to court the geeks. Today marks the opening of the 36th annual Comic-Con Intl., and nearly every studio, along with numerous broadcast and cable networks, has big plans to woo the nearly 100,000 attendees – fans that marketers consider key to building good buzz. Despite flops like this winter’s “Elektra,” comicbooks continue to be hot in Hollywood, with both “Four” and “Batman Begins” among the summer’s few bona fide hits. Comic-Con has grown into a pop culture event encompassing not just comics but genres including sci-fi, horror and fantasy as well as animation. That means most big-budget movies, as well as an increasing number of TV hits like “Lost,” may appeal to Comic-Con attendees. As a result, numerous networks and studios are shipping their stars to San Diego to unspool exclusive clips and answer questions. Most anticipated by fanboys in attendance: Universal’s “King Kong” and Warner Bros.’ “Superman Returns,” both of which have a solo hour in a cavernous hall on Saturday, the confab’s most heavily trafficked day. Other pics will be featured as part of a studio’s multifilm presentation or in smaller rooms.