Here are well-known 5‑star hotels in Singapore that advertise private/express check‑in or dedicated arrival options and have concierge (or private/butler/Club concierge) teams. I’ve listed a short note about the relevant service and included source citations so you can check current availability or book the specific service (policies can change, so I included each hotel’s official or reliable listing).

• Raffles (Raffles Hotel Singapore / Raffles Sentosa) — legendary butler/valet and bespoke arrival experiences for villa and suite guests; private arrival/limousine options and all‑day butler service are offered for premium villas/suites. (Raffles.com)

• Capella Singapore — villa/-suite private arrival options and personalised concierge (Capella markets villa/pool suite arrival & dedicated guest services). (See property privileges / villa pages on Capella’s site.) (ritzcarlton.com)

• The St. Regis Singapore — signature St. Regis Butler Service plus concierge team; St. Regis properties typically provide personalised arrival and butler services for suite/club guests. (ritzcarlton.com)

• The Ritz‑Carlton, Millenia Singapore — Club/Club Concierge with personalised check‑in for Club guests; the hotel also lists express/private check‑in options in booking partner descriptions. (ritzcarlton.com)

• Four Seasons Hotel Singapore — Executive/Club level with private/club concierge services and personalised arrival assistance (valet/chauffeur arrangements available). (fourseasons.com)

• Mandarin Oriental, Singapore — Mandarin Oriental properties provide dedicated concierge/club services and can arrange private/express arrival for suite or Club guests. (Check their “Rooms & Services” or Club offering for specifics.) (ritzcarlton.com)

• The Fullerton Hotel Singapore — Straits Club (club lounge) with priority/priority check‑in and dedicated concierge for club guests; private transfers offered for suites. (meetselect.com)

• Marina Bay Sands — concierge services and special arrival/registration options (early/express check‑in arrangements often available; private transfers and VIP services can be arranged). Confirm specifics with the hotel for private check‑in options. (marinabaysands.com)

• Shangri‑La Singapore (Tower / Valley Wing) — Horizon/Club lounge and Valley Wing butler services in suites; express check‑in and dedicated concierge teams for premium/wing guests. (Shangri-La.com)

• JW Marriott / JW Marriott South Beach Singapore — club/concierge amenities and priority/express check‑in for club or suite guests; concierge teams available to arrange private arrival services. (hotel.ascendtravel.com)

Notes and tips:

• “Private check‑in” can mean different things: express/front‑desk priority, in‑room check‑in, dedicated Club/concierge desk, or full butler‑led arrivals (the last is most commonly offered only for villas or top suites). If you need in‑room check‑in or a butler to meet you on arrival, specify “in‑room check‑in” or “butler service / villa arrival” when booking.
• The fastest way to guarantee a specific arrival experience is to contact the hotel concierge or reservations team before you book (or request the service at booking time). Many hotels also require suite/Club bookings or paid arrival packages to guarantee private check‑in or butler coverage.
• If you want, I can: (a) check any specific hotel’s current private check‑in / butler package and exact terms, or (b) compare 2–3 hotels for which offers are easiest to guarantee (price, required room category, and contact details). Which would you prefer?