I felt frustrated after not being able to dim the background in the photo of grandpa, dad, son; so, I went through a few other tutorials and figured out some new tricks. I utilized the selection tools, as well as layers to go in and adjust the saturation levels of both the ceiling and the window. It's still not perfect, but it is MUCH better (I think). Ideally, when I have the chance to take a photo like this again, I'll be more careful with the background.
Here are the original photo and the adjusted photo:
I still have lots to learn, but this (tiny) victory has me feeling pretty good.