> Parenthetical clauses should be placed inside a sentence. If they are at the end of the sentence, you do it like this:
> Bob married Barb (she was a cute tall redhead).

I would tend to do it this way: "Bob married Barb. (She was a cute tall redhead.)" But your way is valid.

If what's inside the sentence isn't a complete sentence, it cannot stand alone like that: "Bob married Barb (a cute tall redhead)." is the only option for that one.