The playthings we do keep on the main floor are disguised. (I like 'disguised' better than 'hidden' because my kids know where their toys are.) We have dozens of bins, baskets and organizers devoted to this purpose. There is a console behind our couch chock full of toys but you'd never know by looking at it.
Our entertainment console has even more kid-friendly storage.
We have a small table in our sunroom that stores Lincoln Logs.
At the end of the day, we all pick-up together and everybody knows where everything goes. All of this makes me a happy girl at the end of the night when I'm sittin' on the couch with my hubby. Pretending we don't have kids. Until one of them cries.