Nai Yang Beach: first beach where we have been spending a few days, it is very close to our hotel and perfect with kids!
This beach is very popular with Thai locals as well as tourists! You can rent an umbrella with 2 mats for only $5 a day but then you will have to stay in the most crowded part of the beach, so you can walk a little further down on the beach and find barely anyone, use the trees as shade and enjoy peace and quite!
In fact parts of the of the beach are inside Sirinath National Park so once the sun is too hot you can sneak in the park area, enjoy the breeze or lay on an hammock and take a nap. Once you get hungry there are plenty of awesome restaurants everywhere and they all serve thai and some european food as well. If you want to relax more then you can step in one of the many massage places, some are also on the beach.