Good luck, and I hope you managed to avoid Typhoons in HKG, MNL & TPE. The HKG tax is only HK$50 (US$7) but is most likely to be included in your ticket already. The airline lounges do close overnight, but I did once meet a backpacker who had spent the night curled up in the Plaza Premium Lounge (pay entry HK$200). She did have to beg permission though, but worth a shot if you are desperate. To be honest, if you have to stay the night in HK airport Regal Hotel, consider getting the train into town HK$70 e/way, it is only 25 mins direct, there may be better prices in the tourist hotels in Kowloon (and change of scene from airports). Keep us posted.