I want a big slide somewhere.  In the house or outside, or both.  Maybe one that goes from the top floor to the basement.  I want a spiral staircase too.  An elevator somewhere would be nice.  not a big one, even just a one person closet type, but an elevator none the less.  Secret passage ways are a must.  even if it's just a ladder hidden in a wall to get to the floor above.  Not that I want this to be a big play house, i think those features would have practical use to them.