Short answer

• Use major global OTAs (Booking.com, Expedia/Hotels.com, Agoda) for range and deals; compare with Airbnb for villas/guesthouses. (Booking.com)
• For safety and extras (best service, perks or lower rates), also check the hotel’s official website or call/email to book direct. The Sri Lanka Tourism Development Authority (SLTDA) lists and registers legitimate accommodations — good to verify smaller places. (sltda.gov.lk)

Where to search (recommended sites)

• Booking.com — best coverage for hotels, guesthouses and free‑cancellation filters. (Booking.com)
• Expedia / Hotels.com — good for package deals (flight+hotel) and member discounts. (Expedia.com)
• Agoda — widely used in Asia and often shows many small guesthouses and mid‑range hotels. (Tip: always compare prices across sites.)
• Airbnb — private homes, villas, and longer‑stay rentals.
• Hotel chains / luxury collections (e.g., Leading Hotels / Small Luxury Hotels / big brands) — check their official sites for member rates and guaranteed benefits.
• Local options: many small guesthouses and homestays aren’t always listed on global OTAs — check the SLTDA list or contact the property directly. (sltda.gov.lk)

Best areas to search by trip type (quick guide)

• Colombo — city hotels near business, dining and the airport transfer routes.
• Galle & South Coast (Unawatuna, Mirissa, Weligama, Bentota) — beaches, whale watching, surf spots.
• Kandy / Cultural Triangle (Sigiriya, Dambulla) — cultural sites, hill country access.
• Ella / Nuwara Eliya — tea country, scenic train rides and cooler highlands.
• Yala / Udawalawe / Wilpattu — wildlife safaris.
• East Coast (Trincomalee, Arugam Bay, Pasikudah) — best season differs (note monsoons); check dates before booking.
  (General travel guides and destination lists discuss these regions; cross‑check seasonality when you plan.) (thetimes.co.uk)

How to get the best deal and avoid problems

• Compare at least 2–3 sites (Booking, Expedia/Hotels.com, Agoda, plus Airbnb).
• Check cancellation and payment terms — prefer free cancellation if plans might change. (Booking.com)
• Book direct with the hotel when: you want loyalty benefits, a better rate, special requests, or to confirm transfers — many Sri Lankan hotels respond quickly by phone or email. (sltda.gov.lk)
• Verify small guesthouses/homestays are SLTDA‑registered if you want officially licensed accommodation. (sltda.gov.lk)
• Read recent guest reviews (last 6–12 months) and check recent photos; watch for repeated complaints about no‑show or cancelled OTA bookings (happens occasionally with small properties). (reddit.com)

If you want, I can

• Look up best hotels for specific dates and budget, or
• Compare prices for a specific hotel across Booking/Expedia/Agoda and the hotel’s direct rate.

Which would you prefer?