I'm considering a cheek augmentation but my cheekbones are ok when I smile. What would you recommend? (photos)

It appears that your deficiency is actually under your eyes (tear troughs) and in the medial part of your cheek (close to the nose).  I would recommend a small amount of fillers in both of these regions (e.g. Restylane, Belotero) using a microcannula to avoid bruising and to have a safe filling of this region.  

Cheeks can augmented in different places on the face and with implants or fillers.  It would be possible to augment the area just over the cheek bone and this should not look odd when you smile.  Most of the fullness that you get with smiling is on the middle part of the cheek and the augmentation can be done above this area.  The amount of augmentation can also be varied by the amount of filler used or the size of the implant placed.