According to the Steam Family Sharing FAQ:
Can all Steam games be shared with friends and family?
No, due to technical limitations, some Steam games may be unavailable for sharing. For example, titles that require an additional third-party key, account, or subscription in order to play cannot be shared between accounts.
I understand that if I am playing any game in my shared library other people cannot use my games. However, when I am playing my own non-shareable game will other people be able to play my shared games?
Sorry if this seems an odd question. I am trying to understand the feature limitations. Basically, if there is no such limitation I could start up one of my non-shareable games whilst a family member continues playing a shared game. I just want to know if that is actually an option.