A few months ago our family got a new kitten, which put our cat count at three. Beyond two cats, it's a challenge keeping your house from smelling, so my requirement for the kitten was investing in a high quality automatic litter box.
We had tried cheaper units in the past for vacations, and they never worked well. While it was expensive, we got a Litter Robot and I have to say, it is worth every penny. No smell, automatic, reliable, easy to dump litter, no proprietary consumables.