We have 1 MOE hanging diaper pail (glorified pail liner) that we use without a traditional pail. The washer is in the basement and the stairs are steep, so for us it would be a pain to lug a pail up and down the stairs. I try to do the diaper laundry when DS is sleeping, so it works okay to have 1. When it works out that we have a wet/soiled diaper to deal with while the bag is in the wash we leave it on the end of the changing table. I think it would probably be most convenient/efficient to have 2 pail liners though (if you use liners--I think if our washer was on the same level of the house as the pail we would probably go liner-less). We are having another baby this fall, so I plan on getting another bag for dirty dipes.