If you are looking for a very quiet café/ restaurant, you should go to the Du Mien Garden Restaurant. It is quite far away from downtown, but with a motorbike you can get there easily. The atmosphere is really nice and the little “pool” in the middle is the main spot of this café. For me as a Western person (used to snow in Christmas time), it is really crazy sitting next to a pool with Xmas decoration!!
I had a salad there (not really coffee style..) but it was really hard to get vinnegar and oil- but they managed it and finally I had my salad with dressing! My friends tried the sweets (Black forrest cake and cheesecake) and the coffee was also really nice.
The prices are quite high, especially for this location outside D1 and D3, but for the atmosphere, it is worth it!