WITH a three-night tour to Singapore costing $2,900 per person sharing (so $5,800 per couple, $3,700 single), there must be a catch. Actually, there are two. There are only a few seats at that price - the number is unspecified; but is probably no more than 20 on each flight - and the offer is only valid on fixed departure days. The package includes economy class air fare on United Airlines, three nights' hotel room, daily full breakfast, tax and service charges. There are seats on UA flights on November 4, 18, and December 2. The hotel used in the package is the Ladyhill. Other hotels are the Rasa Sentosa, the new Shangri-La managed hotel on Sentosa island, but off the track for a business traveller, and the ANA Hotel, on Nassim Hill. These two hotels cost about $200 to $300 more on the basic per-person package price. The United flights arrive in Singapore late on the first day and leave early morning on the fourth day. So even though this is billed as a four-day package, there are only two days in Singapore in practical terms. Contact Farrington Travel, phone 802-7111, or fax 802-0636. DRAGONAIR is adding business class cabins on its non-China routes flown by Airbus A320s. Starting from today, the aircraft will have 12 business class seats. The service will be typical business class, including 30 kilograms of baggage allowance. Contact Dragonair reservations, phone 590-1188, or fax 590-1331. TWO hotel groups have joined the Thai Airways' frequent flier programme. Members of the Thai programme will receive 500 miles per stay at Sheraton hotels (not for each night - as with most FFPs). The rates paid to qualify must be either full published rates, corporate rates, or the business rates in the company's Suresavers programme; nothing if you are using a special offer or a tour-package rate. You cannot earn miles at all Sheraton hotels; in Asia Pacific, 26 out of 44 of the group's hotels take part. However, all major destinations are included; the main exclusions are its hotels in India. The other group joining is Royal Garden Resorts. In the introductory period, you earn 1,000 miles for each stay, but after December 20, this is due to become 500 miles per stay. However, miles are earned only if you pay full or corporate rates at the group's hotels. Royal Garden has hotels only in Thailand - in Bangkok, Pattaya and Hua Hin. Contact Thai Airways reservations, phone 529-5601. THE Hyatt in Macau has introduced a package, but running only until November 7, to link-in with the enclave's music festival. The cost is $375 per person sharing (so $750 per couple) during the week, including pier-hotel transfers, buffet breakfast, and one-way transfer to the festival. Saturday nights cost $525 per person sharing (so $1,050 per couple). And another Hyatt, the Grand Hyatt in Taipei, has a package running through the winter costing NT$4,200 (about HK$1,220) nightly - which seems high but full basic rates start at NT$5,200. The package price includes full breakfast, laundry and pressing of two items of clothing. The offer expires March 31. Contact Wyatt reservations, phone 739-1234. A NUMBER of hotels in Sydney have put together packages with tickets for the acclaimed musical, Phantom of the Opera, showing at the Theatre Royal. Packages are similar - one-night hotel room, two tickets to the show, and chocolates and a glass of champagne at the theatre. At the Regent, that package costs A$400 (about HK$2,000), including transfers to and from the theatre; at the Sheraton A$375, including breakfast; and at the Observatory, part of the Orient Express group, A$490, including breakfast. Contact Regent reservations, phone 366-3361, or fax 721-4400; Sheraton reservations, phone 739-3535; and Dodwell Travel, phone 866-6699, or fax 866-0863, for the Observatory. NATIONAL Car Rental is selling weekly car rental in Europe for the equivalent of US$174 (about HK$1,350) in France, US$122 in Germany, and US$131 in Britain. These rates are not normally available in Hong Kong. These are for 'sub-compacts' (usually mini, three-door cars), and include unlimited mileage but exclude tax and optional CDW (to waive the requirement for the company to charge you for the first US$1,000 of damage), and must be booked 14 days in advance. The rates are called AdvanSaver. Book through travel agencies. Information compiled by Travel Database, GPO Box 12761, Hong Kong. Fax 507-4620.