I'm not very good with play. It depends on the activity and the day i suppose. If they are well and happy I set them up and leave them while i do other things, if they are sick or grumpy then i play with them. DH is the master player in this house, any time they play together it turns into a giggle-riot
I tend to focus on my relationship with them in other areas, we talk a lot about all kinds of things, read heaps of books, do crafty stuff. I have a great relationship with both of them so we are doing something right !