THE hotel industry sector of the Hongkong stock exchange came to life last week with the announcement of Lai Sun Development acquiring the 214-room Ritz Carlton hotel. Apart from that, stocks traded on a dull note. According to Sun Hung Kai analyst Brian Oung, Mandarin Oriental and Hongkong and Shanghai Hotels are performing well. ''The two stocks are considered blue chips and getting expensive. This means that second-and third-line stocks like Regal and CDL stand a chance of going up,'' he said.