In my last house (bungalow), I had plans to use the basement, but didn't want to make the switch until we added a bathroom down there. That never happened. So I had the bedrooms nice and close for napping, and daycare stuff was mixed in with our own things. If I had stayed there I would have moved to the basement to get more space, and to keep my personal space less cluttered.
In my current house, the previous owners had done a nice job converting the attached garage into living space. So I converted that living space to a daycare room, and I love it. We are close to the kitchen and bathroom, and have access to the yard without having to manage stairs everyday. The only thing I miss about my old place was how nice and cool the basement stayed all summer. And now the bedrooms are on the second floor, so the kids don't have any bedrooms to nap in. They are just spread out everywhere on the main floor.
Every interview I've done in my new house, parents have loved all the natural light and separate main floor daycare room.