One of our favorite things to do is watch the girls play. They have a huge room to play in that we have blocked off with baby gates. We lovingly refer to the room as "romper room".
They are so much fun to watch, you can see the gears in their brain working and trying to figure out how something works, how to make the noise and what the toy does.
We love going into romper room and playing with the girls. Since they are both "pulling up machines" they use us a human jungle gyms and we love it!