Sri Thanu is like the suburbs, not the ones that are far away, the ones that are near the city center, but seems like they are far away. It is good place for couples who are mainly into staying at their room and do whatever couples do. Being close to Thong sala is a bonus, and the views are great.
Chaloklum is the opposite of Haadrin, both geographically and conceptually, it is a quiet fishing village in the north tip of the island, not very expensive or flashy it is suitable for people who wants a bit of quiet time. There are couple of shops, restaurants and bars around so you will not feel completely isolated, but you will have to travel a bit if you want to really go out. If you are cool with boredom and just want to relax this is the place for you.