For fine dining, Ruen Urai no regret. Every dishes have it own "character" and the "after taste" is just lovely. Compared to other big name like Issaya Siamese Club, it is much better in term of taste.
Mango sticky rice must be Mae Varee even they only offer take away. The mango is sweet and do not have 渣.
if you want to try something local and like beef, can try Heng Chun Seng.