Below is a 5-day luxury Sri Lanka itinerary that includes Bentota Beach and balances relaxation (beach, spa, private dining) with culture (Galle, Kandy). I assume you’ll fly into Colombo (Bandaranaike - CMB). I include suggested 5-star hotels, approximate transfer times, high-end activities, and booking tips.

Quick logistics (useful for planning)

• Colombo (CMB) → Bentota: about 1–1.5 hours by private car (≈63–65 km). (Rome2rio.com)
• Bentota → Galle: about 1 hour by car.
• Galle → Kandy: around 3.5–4 hours by car (longer if you stop).
• Kandy → Colombo: around 3–4 hours by car, or take the scenic train (book 1st/2nd class observation seats).
  (If you prefer a different order—e.g., Colombo → Kandy → Galle → Bentota—that’s also workable but involves more driving.)

Day 1 — Arrival & luxury beach time in Bentota

• Morning: Land at Colombo (CMB). Meet a private transfer/driver and drive to Bentota (1–1.5 hrs). (Rome2rio.com)
• Hotel suggestion (Bentota): Cinnamon Bentota Beach — classic luxury on the sand (refurbished Geoffrey Bawa property, strong beachfront location and resort facilities). Ideal for a first-night unwind. (en.Wikipedia.org)
• Afternoon: Private beachfront lunch, unwind by pool or on the beach, enjoy an introductory Ayurvedic spa treatment or private yoga class.
• Evening: Sunset private seafood dinner on the beach or chef’s tasting menu at the resort.

Day 2 — Bentota: river safari, wellness & water-sports

• Morning: Bentota River (Madu Ganga) private boat cruise — mangrove exploration, birdwatching, optional visit to a cinnamon island or small islands; consider a private naturalist guide.
• Late morning: Visit the Sea Turtle Conservation Project (Rehabilitation center) for an educational, behind-the-scenes visit (arrange private access through your hotel concierge).
• Afternoon: Return for a signature spa ritual (Ayurveda/panchakarma session or couple’s spa) and some luxury water-sports (private jet-ski, stand-up paddle board or a guided snorkel if conditions allow).
• Evening: Sunset cocktails, private beach barbecue or a degustation pairing at the hotel.

Day 3 — Transfer to Galle & heritage luxury

• Morning: Short drive to Galle (≈1 hour). Check into a heritage luxury hotel inside or overlooking Galle Fort. Two excellent choices: Amangalla (inside Galle Fort, ultra-luxe, heritage) or Jetwing Lighthouse (coastal, designed by Geoffrey Bawa, luxury ocean views). (en.Wikipedia.org)
• Midday: Private guided walking tour of Galle Fort (UNESCO World Heritage site) — colonial architecture, boutiques, art galleries, and rooftop cafés. Arrange a private historian/guide for depth.
• Afternoon: High tea in the fort, then return to hotel for leisure (pool/sea views). Optional short boat trip to see stilt fishermen (seasonal).
• Evening: Private dinner in a restored colonial setting or private rooftop dining overlooking the fort and ocean.

Day 4 — Transfer to Kandy (tea country & culture)

• Early morning: Private transfer to Kandy (≈3.5–4 hours). Option: split the drive with a stop at a tea plantation/viewpoint for photo breaks.
• Hotel suggestion (Kandy): Mahaweli Reach or another 5-star riverside hotel — luxury with easy access to Kandy’s cultural sites. (Mahaweli Reach is a long-established 5-star in Kandy.) (en.Wikipedia.org)
• Afternoon: Visit the Temple of the Tooth Relic (Sri Dalada Maligawa) with a private guide; explore Kandy lake and Royal Botanical Gardens (Peradeniya) if time permits.
• Evening: Traditional Kandyan dance performance (private seating), followed by a candlelit dinner at your hotel.

Day 5 — Kandy leisure, scenic option and departure Option A — If your flight is late evening:

• Morning: Leisurely breakfast, then a private visit to a tea factory nearby with a tasting and private tour of the plantation.
• Option: Take the scenic train from Kandy toward Colombo (book 1st/Observation/AC seats in advance) for a memorable ride and have your driver meet you at the Colombo end—then transfer to Colombo for final departure. (Train is scenic but can take longer — reserve seats early.) (adelaidenow.com.au)
• Afternoon: Transfer to Colombo (3–4 hrs by car) with drop-off at the airport (allow 3 hours before international departures).

Option B — If your flight is early:

• Depart Kandy early by private transfer straight to Colombo Airport (allow ~4 hours total travel + recommended airport arrival buffer).

Booking & practical tips (luxury traveler checklist)

• Private transfers and an English-speaking driver-guide: book through a reputable DMC or your hotels’ concierge for meet-and-greet and flexibility. For a luxury trip, a private air-conditioned vehicle with Wi‑Fi and water is standard.
• Hotels: reserve suites or villas with private verandas/pools where available. Cinnamon Bentota, Amangalla (Galle) and Mahaweli Reach (Kandy) are reliable luxury picks. (en.Wikipedia.org)
• Timing: road travel times in Sri Lanka can vary with traffic; add 20–40% buffer to daytime estimates. For any intercity plans (especially trains and domestic flights), book early.
• Health & visas: check Sri Lanka visa requirements and health advisories before travel (vaccinations, malaria risk)—your travel agent or embassy site will have current rules. (I can look these up if you’d like.)
• Best season: For the southwest coast (Bentota/Galle) the best months are typically December–April for dry, sunny beach weather; rains may affect activities outside those months—confirm dates when booking.

If you want, I can:

• Convert this into a day-by-day printable itinerary with specific hotel contacts and dining recommendations.
• Price estimates for private transfers, hotels (examples by category), and private guides.
• Swap Kandy for Sigiriya / Cultural Triangle (possible but adds extra driving or a domestic flight).

Which of those would you like next?