My DS does a mixture - he is happy to play alone for a bit but likes to see that we are around - he v rarely would go into another room if he cant see us. i encourage this as i think it is good for his creativity, but i also love playing with him, seeing what he is up to etc. i think they would play alone more when they are a bit older and esp when they go to school etc (like mbear's dd) when they are around lots of other kids all day...