If you want to visit a nice sand beach , but don’t want long traveling. May I recommend you Hua Hin. Hua Hin is a very nice beach with white sand, clear sky and calm sea. You can drive there about 2 hrs from Bangkok. There are many nice resort and boutique hotel. In Hua Hin town there are many good restaurants (Thai-Indian-Italian-Chinese food) also ” Starbucks ” if you are someone who addict coffee. Then you can try horse riding and gun shooting too.
Anyway I would like to recommend you visit ” Maruekkatayawan palace ” that is King Rama 6th ’s palace. This palace made since 1923. This place is on the way to Hua Hin, it is between Cha Am district and Hua Hin district.
More detail Maruekkatayawan
Other place that you should visit : Kao Wang and Kao Luang cave.
More detail Hua Hin