]Mr. Bennet called Mrs. Bennet "Mrs. Bennet", but I kind of thought they were just being, well, mean to each other, in their Mr. Bennet vs. Mrs. Bennet way.

Etiquette books of the period and a little beyond said that is was a sign of respect to call your spouse Mr or Mrs in company and when refering to them in conversation. First names were reserved for private moments. Mr. and Mrs. Bennet were actualy showing respect,:) but since they never seem to call each other anything else, not even in front of their own children, I always saw it as a sign that they were not close.