Apartment Keys
I don't generally lock my doors. I rarely have random intruders. One thing I was wondering, though, is if the doors are locked in an apartment, can a Sim who's been given an apartment key still get in...
Forum Discussion
As for locking doors for specific Sims... yes and no. You can only specify them when they're present in the neighbourhood if I recall correctly. The most efficient way I'm aware of is to lock the door for everyone but household, then when others come to visit, use "Unlock Door for..." to give them access.
