Here are the top ultra‑luxury resorts in Sri Lanka (best for service, design, privacy and unique experiences). I’ve listed each with where it is, what makes it special, who it’s best for, and a quick booking tip.

1. Cape Weligama — Weligama / South Coast

• Why go: Dramatic cliff-top villas and suites with large terraces and an iconic crescent “moon” infinity pool, outstanding cuisine (Relais & Châteaux standard) and whale‑watching off the coast. Best for couples and families who want dramatic ocean views and luxurious villa space.
• Booking tip: Book a villa with private plunge pool and request whale‑watching timing at booking for peak season (Nov–Apr). (thenationalnews.com)

2. Amanwella (Aman) — Tangalle / South Coast

• Why go: Minimalist Aman design, private low‑rise suites, long semi‑private beach, exceptional privacy and understated service — one of Sri Lanka’s benchmark ultra‑luxury beach retreats. Best for privacy, wellness and high‑end service.
• Booking tip: Book early for ocean‑facing suites during December–March; surf lessons available on request. (cntraveller.com)

3. Ceylon Tea Trails — Hatton / Hill Country

• Why go: Restored colonial planters’ bungalows set on a working tea estate—intimate, historic luxury with immersive tea experiences and panoramic hill‑country views. Best for slow, romantic stays and tea lovers.
• Booking tip: Bungalows are few—reserve well in advance for peak months (Dec–Feb). (vogue.com)

4. Santani Wellness Resort & Spa — Near Kandy / Hill Country

• Why go: High‑end wellness retreat focused on Ayurveda, personalized programs, minimalist contemporary design and new private villas with plunge pools. Best for health, detox and design‑minded travelers.
• Booking tip: Book a wellness package (detox, Ayurveda or yoga) rather than room‑only for the best experience. (wallpaper.com)

5. Wild Coast Tented Lodge (Uga Escapes) — Near Yala National Park / South‑East Coast

• Why go: Ultra‑stylish luxury “cocoon” tents on a wild beach bordering Yala — combines glamorous camping with top service and excellent wildlife/safari access (leopard country). Best for adventurous luxury and wildlife.
• Booking tip: Combine tented‑lodge nights with private game drives; book safari slots in advance. (telegraph.co.uk)

6. Jetwing Vil Uyana — Sigiriya / Cultural Triangle

• Why go: A unique eco‑luxury property built on an artificial wetland with private paddy and marsh villas, exceptional for birding, design and sustainable architecture. Best for nature lovers and culture itineraries (Sigiriya).
• Booking tip: Ideal base for early morning Sigiriya climb and cultural excursions—arrange guides through the hotel. (en.wikipedia.org)

7. Galle Fort Hotel / Amangalla — Galle Fort (Heritage)

• Why go: For colonial heritage luxury stay inside Galle Fort: period architecture, private historical atmosphere and easy walking access to Galle’s boutiques, restaurants and fort ramparts. Best for culture and romantic city stays.
• Booking tip: If you want the grand colonial feel choose Amangalla (restored governor’s‑style suites); book a fort‑view room. (en.wikipedia.org)

8. Saman Villas (Jetwing) — Bentota / South West Coast

• Why go: Intimate cliffside villa property with large suites, private pools and personalized service—longstanding boutique luxury on the southwest beaches. Best for couples seeking privacy near Bentota.
• Booking tip: Private‑pool suites are limited—reserve early for holiday season. (en.wikipedia.org)

9. Uga Ulagalla (Uga Escapes) — Anuradhapura / North Central

• Why go: Large private villas in a restored rice‑paddy estate, strong on privacy, cultural touring (Anuradhapura, Sigiriya) and rural luxury. Best for families or groups wanting villa‑style seclusion.
• Booking tip: Villas are spacious—good for multi‑night cultural circuits combining hill country and coast. (en.wikipedia.org)

10. ITC Ratnadipa / Shangri‑La Colombo (City luxury)

• Why go: For ultra‑luxury in Colombo: modern five‑star facilities, fine dining and central location for business or as a launch point for the island. Best for arrivals/departures, city‑side shopping and dining.
• Booking tip: Use Colombo hotels for a final or first night when arriving late or catching international connections. (en.wikipedia.org)

How to choose (quick):

• Beach + privacy: Amanwella, Cape Weligama, Saman Villas.
• Wellness/Detox: Santani.
• Wildlife + unique landscapes: Wild Coast Tented Lodge, Jetwing Vil Uyana.
• Hill country & tea experience: Ceylon Tea Trails.
• Heritage + culture: Amangalla/Galle Fort Hotel, Ulagalla.
• City luxury: ITC Ratnadipa, Shangri‑La Colombo, Cinnamon Lakeside.

Practical booking tips

• Best time: South/west coast and Yala — November to April for calm seas and whale season; hill country cooler year‑round (peak Dec–Feb).
• Book early for December–January and school‑holiday periods; villas and bungalow‑style rooms sell out.
• Transfers: Many ultra‑luxury resorts offer private transfers (car, seaplane or domestic flight + road transfer)—confirm transit times when you book.
• Packages: Look for inclusive packages (meals, activities, spa credits) which often add value at top properties.

If you’d like, I can:

• Narrow this to the top 3 for honeymooners, families or wildlife travelers; or
• Check live room rates/availability for specific dates (I’ll look up current rates and transfer options).