What is it about children's hospitals that makes them such nice places?

Today I visited a children's hospital to provide support to my friend whose young son is staying there. I was really scared and nervous because I thought it would be so gloomy and depressing, but it was actually extremely pleasant. I ended up really enjoying my visit. Now I've been trying to pinpoint what specifically made it such a nice place to be but I just can't put my finger on it. Anyone know?