One evening last week, a woman on the street near Union Square had on a T-shirt that read "Size Matters." She and her companion were wearing shorts; perhaps they were tourists. In any event, she looked embarrassed. Maybe it had nothing to do with the double entendre emblazoned on her chest. But she certainly would have been less uncomfortable had she'd known about the 70MM Festival of ultra-widescreen epics coming soon to a theater near her (if she could only stretch her vacation another week!). For a maximum-strength '80s retro-fix, it's tough to top tonight's pairing of John Carpenter's most endearing and life-affirming sci-fi yarn Starman with Douglas Trumbull's special F/X extravaganza Brainstorm (with Natalie Wood's final screen appearance). 2001: A Space Odyssey, Stanley Kubrick's still-mesmerizing meta-profundity, can be fully grokked only on the big, big screen. And as creepy as Gov. Lederhosen looks on TV, he's even more frightening blown up big as a building in the steroid-infused collar-grabbers Total Recall and Terminator 2: Judgment Day. The dress code? Come as you are.