the robot vacuum is, for me, a definite buy. It runs every second night, or when I think it needs a bit of an extra scrubbing, and keeps on top of the dust and cat hair without me lifting a finger. And given it enjoys eating cables it also motivates me to tidy up regularly.
Also, voice controlled occasional lights because the genius who decided where to put the light switches in my home placed them at the end of long hallways, rather than the beginning. I can now shout at the house to turn them on, and if I leave the house having forgotten to turn one off a geofence turns them off automatically if I get far enough away.