Thailand Holiday Planning?

My husband and I went to Phuket earlier this year for what was supposed to be our honeymoon but was ruined by booking problems with our travel agent and really, really bad accommodation and service. We are planning to go back next year to try again but do not want to go back to Patong. We are tossing up between Koh Samui, Khao Lak and/or Kata Beach. We will be making a stop over in Bangkok. Can anyone advise out of these 3 which they would recommend? We want relaxation but also want to be fairly close to shopping and restaurants. Thanks!