LOS ANGELES, Calif. -- On a balmy evening earlier this month, wealthy guests in backless gowns and tuxedoes gathered to toast the city's newest high-end hotel, SLS, which boasts such amenities as poolside concierges and in-room massages. But no amount of top-shelf liquor could dull the dreary outlook confronting SLS and the cadre of recently opened luxury hotels. In Los Angeles, where self-indulgence rises to art, SLS splurged on a $700,000 opening party. The company has already begun offering discounts for its freshly minted rooms, showing how the deep strains on the hotel industry are being felt even here.