Extra Time in Paradise

pending an additional few weeks in Phuket or Krabi would give me more opportunities to explore smaller beaches and local markets. Since visa extension procedures are discussed at https://mythai.online/gid/prodlenie-vizy-v-tailande/ I'm wondering how travelers usually fit the paperwork into their plans. I'd especially enjoy spending time in a quieter coastal town where I could relax and get familiar with the local lifestyle. An extended holiday would also give me a chance to visit nearby islands without rushing between destinations. Which Thai destination would you choose for an extended stay?