To be onest, Accor is very poor in Thailand, especially if you speck about “resort” ...

i like So Sofitel and much more Sofitel in Bangkok but I don’t like any property in Phuket and Koh Samui

even Sofitel in Krabi was really below my expectation

about the list below i’ve been and would not recommend the following

Krabi:
Hotel Sofitel Krabi

Phuket:
Pullman Phuket Arcadia Naithon Beach
Pullman Phuket Panwa
Avista Hideaway Phuket Patong

Pattaya:
Pullman Pattaya Hotel

Koh Samui:
Novotel Samui Resort Chaweng Beach
Mercure Koh Samui Beach Resort

Phuket:
Hotel Novotel Phuket
Hotel Novotel Phuket Kamala Beach
Hotel Novotel Phuket Surin Beach Resort
Novotel Phuket Kata Avista Resort and Spa

Pattaya:
Novotel Pattaya Modus

P.S. If you will go in Koh Samui, stay at Poppies or Vana belle

if you will go in Krabi, stay at Rayavadee

if you will go in Phuket, stay at The Surin