You may start with a little house, but as your family grows,
so must your home, at least during the years the kids are around.
This existing house (pictured below) was not expected to stand as
 long as the new construction, so I designed the new living space as
a separate, structure, with a simple, attractive  'greenhouse bridge'
spanning between, which serves to shelter and define the wide stairs
between the buildings, which leads down to the lake from the parking 
area above. The upper 'old house' contains the children's areas, while
its separate lower level houses the utility and work spaces, as well as
being a guest area for privileged relatives and friends (who may have
helped in the owner building) to visit the lake/beach, change clothes,
cook, and even spend a night, without encroaching into the family's
more private living spaces, or even needing to awaken them. Once
there is a desire to downsize, everything they need is available
in the space of the new little house.   Both of the structures
are Solar heated, via sunspaces and south facing windows.