im with a lot of you other guys - shoulder. specifically lateral head. if i do particularly well on an overhead press the next day i might get a little bit but nothing like chest or back.
side note - every time i do shoulders my traps KILL the next day. think that might be a contributing factor
For me shoulder wise it's only DB lateral variations that don't make me sore... sitting a lateral machine where I'm able to "grind" reps a bit more almost always makes me sore.
Presses still make me sore to a certain degree in the side delt, wider grip upright rows and machine laterals all will do it.
I didn't read all the posts carefully, but as a few mentioned shoulders and calves definitely. Even if going very heavy on old school, load up the bar on your shoulder, calve raisers
Another part for me when I am in a really good long time period of not missing a workout is my back when I am NOT doing deadlifts. Not sure why but it rarely gets sore anymore, particularly middle upper.