Singapore Airlines typically offers Business and Economy cabins (with First or Premium Economy on some widebody/long-haul routes). Cabins differ notably in seating, catering, baggage allowance and mileage accrual.
For short routes economy is usually the best value; on overnight or long-haul flights Business meaningfully improves rest. Watch for upgrade offers with miles or cash around check-in time.
Product-wise: Singapore Airlines perennially tops world-airline rankings, linking six continents through Changi. Its A380 Suites and consistently excellent cabin service set the industry benchmark; KrisFlyer miles work across Star Alliance and with Scoot.
On loyalty: KrisFlyer members accrue miles by cabin, and elite tiers add seat, baggage and lounge benefits — worth joining if you fly Singapore Airlines often.