Last night (their second with us) we gave them freer run of the house. Saki decided that burrowing under the duvet with us was a good idea - this appears to be something imprinted into the DNA of Abbies. Toto is somewhat less brave than his sister and didn't do so, but the pair were to be found on the covers this morning.
They definitely approve of the main staircase, which has a narrow ledge outside the bannisters along the upper landing such that when the stairs bend through 180 degrees, this ledge provides a perch above the lower steps from where they can see into the hallway and kitchen. It's an ideal place for them to sit and watch the world.