I boil 4 cups water in most cases. I often make a couple cups more later for tea time (it has become something a couple of us ladies do - we have after dinner tea :p )

4 cups seems to be perfect for me - enough for dinner, drink and I can clean up my hands/face as well - warm water is so nice in winter.

My pot choice changes by the trip - but if going light I carry a tea kettle that holds said 4 cups