A VARIETY of Discovery Tours holiday packages are available year-round from Cathay Pacific combining Penang in Malaysia with other destinations such as Langkawi and Lake Toba (Sumatra). Prices range from $5,200 per person for a five day-four night tour to Penang to $7,950 for a seven day-eight night tour taking in Penang, Lake Toba, Brastagi and Singapore. The packages include hotel accommodation, American breakfast, transfers and insurance. NEW Zealand's world-class hiking routes are traditionally closed in winter (our summer), but for the first time this year the South Island's alpine Routeburn trail will be available through a package hiking program that includes meals and accommodation. It may be cold, but the winter walks have one advantage. They're free of the mosquitoes and sand flies that can plague hikers in summer. Contact the New Zealand Tourism Board, Tel 526-0141. HYATT Regency Macau has introduced a weekend package which includes child care if the child is under five. The cost is $1,980 for two adults and one child under the age of 12 sharing a room for two nights, plus daily buffet breakfast for three and other extras. VIETNAM has cut the time taken to travel the ''Reunification Express'' from Hanoi to Ho Chi Minh City to 36 hours, down by half in five years. Rail authorities have invested $28 million in upgrading signals and other equipment along the 1,729-kilometre rail line, which was heavily damaged by bombs during the Vietnam War. BUY one full fare SAS business class return ticket to Europe and receive another one free if you travel before May 31. To qualify for the offer you must become a member of the SAS EuroBonus frequent-flyer programme. Phone SAS, 526-5978 for more details.