Sierra Towers sits on Doheny Road at the western end of the Sunset Strip, where the lively commercial clutter of West Hollywood gives way to the grand mansions of Beverly Hills. The building has always had its fans, well-heeled Westsiders of a certain age who appreciated the unobstructed views from every floor and the tender ministrations of porters and attentive doormen. It isn't surprising that condos in the building have been selling for jaw-dropping prices the last few years — the cost of residential real estate has skyrocketed throughout Southern California. Yet a Sierra Towers address now represents something more than a hefty price tag: The building has acquired a cool quotient.