Kissing, licking, nibbling and playful biting options in poses.
Lets use the doggy pose as an example.
I like to describe how I slowly stroke her back, just feeling her. Running my fingers up and down her back, barely touching her skin ... just teasing. Leaning it to kiss, lick and bite her playfully all over. Slapping her ass, then squeezing it hard ... or both cheeks at the same time

In my opinion this would greatly add to the experience instead of having three or four different facial expressions.