Great — here are top family-friendly resorts in Sri Lanka (spread across the south, west and north-west coasts), with what makes each good for families and a short note on age-suitability or family facilities. I recommend confirming specific kids’‑club hours, babysitting and family-room options before you book (many hotels change schedules seasonally). Sources: reviews and hotel pages cited after each entry.

1. Cape Weligama — Weligama / South Coast

   • Why families like it: nature-based “Forest School” kids’ club (device‑free activities), family and interconnecting suites, several pools including a family cove pool, kids’ menus and babysitting available. Good for multigenerational stays.
   • Best for: toddlers → teens. (i-escape.com)

2. Anantara Peace Haven Tangalle — Tangalle / South Coast

   • Why families like it: quiet beach cove (Goyambokka), family villas and suites, kids’ programmes and supervised kids’ activities plus easy access to southern coast excursions (turtle hatcheries, boat trips).
   • Best for: toddlers → teens; good for families wanting beachfront luxury and beach walks. (en.Wikipedia.org)

3. Shangri‑La Hambantota (including resort water‑park facilities) — Hambantota / South-East

   • Why families like it: large resort footprint with children’s club, dedicated children’s pools and water‑play facilities, many family activities and excursions. Good for active kids who like pools and on-site entertainment.
   • Best for: young children → teens. (classresorts.com)

4. Heritance Ahungalla — Ahungalla / South-West

   • Why families like it: long beachfront, family rooms, kids’ club and dedicated children’s pools, wide range of watersports and family excursions (river safaris, whale watching).
   • Best for: toddlers → older kids. (bestattravel.co.uk)

5. Dolphin Beach Resort (Kalpitiya) — Kalpitiya / North-West (great for marine life)

   • Why families like it: smaller eco‑beach property with family tents/units, excellent for dolphin/whale watching and easy, safe beach access; great for families who want an activity‑focused stay (kitesurfing/dolphin trips).
   • Best for: school‑age kids → teens who like marine activities. (en.Wikipedia.org)

6. Avani / Cinnamon / Mid‑range beach resorts (examples: Avani Kalutara / Cinnamon Bey / Riu Ahungalla)

   • Why families like them: reliable mid‑range choices with family rooms, kids’ pools/children’s activities and easier budgets; commonly used by families who want beach + convenience near Colombo or Bentota. (Facilities vary by property—check the specific hotel.)
   • Best for: budget‑conscious families and younger kids. (tripadvisor.in)

7. Bentota / Negombo family resorts (examples: Riu Ahungalla, Jetwing Blue, Citrus Waskaduwa)

   • Why families like them: shallow beaches or protected bays, large family pools, animation/kids’ programmes at bigger properties, short transfers from Colombo (useful for short stays or airport nights).
   • Best for: toddlers → pre‑teens. (travelmyth.com)

Quick practical tips when booking for a family

• Confirm kids’‑club opening days/hours and minimum/maximum ages (many Sri Lanka hotels run clubs seasonally or by demand). (tripadvisor.in)
• Ask about interconnecting rooms or two‑bedroom/family suites and whether cots/extra beds are free. (Many hotels supply them but policies vary.)
• If you have very young children, check for lifeguards / shallow family pools and whether the beach has a safe swimming reef.
• For active families, check schedules for whale/dolphin watching (seasonal) and surf lessons — south and west coasts have different best months. (thetimes.co.uk)

If you tell me the region you prefer (south coast, Bentota/Negombo, Kalpitiya) or your budget and children’s ages, I can narrow this to 3–4 exact properties, show approximate nightly rates and give direct contact/booking tips.