Nice choice — Sri Lanka’s central highlands are perfect for slow, restorative stays among tea estates, misty ridgelines and cooler air. Below are highly recommended hill‑country retreats (varied styles: luxury spa, converted tea‑factory hotels, intimate bungalows) with what to expect, best area, ideal length, and booking tips.

Top hill‑country retreats for relaxation

1. Santani Wellness Resort (near Kandy) — design‑led wellness & Ayurveda

• Why go: a dedicated wellness destination with personalized Ayurvedic programs, hydrotherapy circuits, guided breathwork and nature walks; minimalist rooms, digital‑detox focus. Ideal if you want a structured detox/renewal program. (jetsetter-magazine.com)
• Area: foothills near Kandy (easier arrival from Colombo or Kandy).
• Stay length: 3–10+ nights (programs often start at 3–7 nights).
• Booking tip: reserve wellness packages directly (consultation included); arrive a day early to acclimatize.

2. Ceylon Tea Trails (Haputale/Bandarawela area) — restored tea‑planter bungalows

• Why go: five restored colonial tea bungalows scattered across private estate — very private, immersive tea‑country experience with guided plantation walks, butler service and inclusive dining. Great for slow, romantic, low‑tech relaxation. (thetimes.co.uk)
• Area: central highlands (remote; long scenic drive or seaplane + transfer).
• Stay length: 3–5 nights to unwind and explore nearby walks.
• Booking tip: transfers can be long — add a seaplane leg if you want to shorten travel time (seasonal).

3. Heritance Tea Factory (Kandapola / Nuwara Eliya region) — historic tea‑factory hotel

• Why go: converted tea factory with dramatic architecture, tea‑tasting experiences, plantation walks and crisp highland views — combines heritage atmosphere with full hotel services. Good if you want character plus comfort. (en.wikipedia.org)
• Area: Kandapola (above Nuwara Eliya).
• Stay length: 2–4 nights.
• Booking tip: check for high‑tea/plantation‑tour packages and book excursions in advance.

4. Yasmin Hill / GalaVilla (Haputale / Haputalé valley retreats) — Ayurvedic & retreat programs

• Why go: boutique Ayurvedic-focused property and retreat center offering multi‑day programs, yoga and local herbal cuisine; offers group retreats and private Ayurvedic regimens. Good for immersive retreat weeks. (yasminhill.com)
• Area: hill country valleys (Haputale area).
• Stay length: 7–21 days for full Ayurvedic programs (shorter stays possible).
• Booking tip: retreats often run on fixed dates — book early and confirm dietary/medical needs.

5. Theva Residency (Hantana hills, near Kandy) — boutique hillside hotel with views

• Why go: boutique property perched above Kandy with panoramic hill views, infinity pool and spa — a convenient, comfortable retreat if you want hill country calm while staying close to Kandy’s cultural sites. (theva.lk)
• Area: Hantana range, short drive to Kandy.
• Stay length: 2–4 nights.
• Booking tip: great as a one‑to‑two night wellness stop combined with cultural sightseeing in Kandy.

Other options to consider (if you want alternatives)

• Small tea‑bungalows and family‑run guesthouses across Ella, Haputale, Bandarawela and Nuwara Eliya for very quiet, low‑key stays (many offer guided walks and homestyle meals).
• Luxury lodges that combine wildlife/day‑trips with highland stays (useful if you want both relaxation and short excursions).

Practical notes — when to go, travel & what to pack

• Best seasons: December–March is generally driest for most highland sightseeing; the central hills are cooler and misty year‑round, and May–September can be very lush (monsoon patterns vary by microregion). Check exact weather for the specific area before booking. (cntraveler.com)
• Getting there: most visitors combine Colombo → Kandy (by road/train) or Colombo → Nuwara Eliya/Ella by road; rail from Kandy to Ella is scenic but slow. Some luxury properties offer seaplane transfers to shorten travel times (seasonal, extra cost). (thetimes.co.uk)
• Health & comfort: hill country is cooler—bring layers, a light jacket, and good walking shoes. If booking Ayurvedic programs, declare medical conditions and medications in advance.
• Budget: options range from mid‑range boutique (Theva, Yasmin Hill variants) to luxury (Santani, Ceylon Tea Trails, Heritance). Programs (Ayurveda/wellness) usually add to room rates; check inclusions.

Booking tips

• Book direct for wellness packages (many retreats give guaranteed program components and consultations).
• Reserve high‑demand properties (Ceylon Tea Trails, Santani) well in advance, especially for December–March and holiday periods.
• Confirm transfers and travel time estimates with the property (some estates are remote with long drives).

If you’d like, I can:

• Narrow these to only luxury vs budget options,
• Compare 2–3 retreats side‑by‑side (price range, travel time from Colombo airport, exact program lengths),
• Or check real‑time availability and rates for specific dates (I’ll look up current prices and openings).

Which of the above fits your style — full wellness/Ayurveda, colonial tea‑estate charm, or a boutique hill hotel near Kandy?