We will be in Khao Lak in January. I will be 6 months pregnant and so can't dive. I would like to go snorkelling instead, we also have a 2 year old. I can see day trips for either the Similians, Koh Prathong or a Combination trip of Tachai and Prathong. Like most people I would prefer the smaller group and quieter beaches, after the most relaxing day while also doing some decent snorkelling.