Average peasant, average land-owner, or average gentry? I highly recommend Daily Life in Medieval Times, by Frances and Joseph Giles, and if you can find it, Marriage and Family Life in the Middle Ages by the same authors. Another great source is the series A History of Private Life, from the Harvard Press, which is broken down into volumes for different eras.

Some very broad generalities: most families also included unmarried or widowed relatives and unrelated servants, as agrarian lifestyles still needed more hands to raise crops and lifestock; most homes were smallish, perhaps two ground-floor rooms or a ground-floor room and a loft or second floor room; most households had at least one outbuilding to house animals, sometimes many outbuildings for various agricultural purposes; most households either worked together on their farm or in their shop, sending members as needed for supplies or to take products to market; non-agrarian households would often have the front room or downstairs room double as the shop for whatever specialized trade the family was in; many couples had at least one child before being formally married, because the main point of marriage was to produce children and if the union wasn't fertile there was not so much point to it; everyone in the house who was old enough to walk had purposeful work to do to directly contribute to the maintenance and well-being of the household.