Ted - There are a couple of advantages to shooting in 4k that you might want to consider:
First - When you process your video footage (I use Final Cut Pro X from Apple), having a larger frame size allows you to do things like crop or zoom in without losing image quality when you export to 1080p for your home movies (or to post on YouTube).
Second - Technology marches on, and one
day you may find yourself the owner of a 4k TV. At that point, you will appreciate the fact that you shot in 4k.
I do output all my processed videos to 1080p, but shoot in 4k at 24fps. Note that if you want to use slow motion in a video clip, such as a sports clip of your son hitting a home run, shooting at 60fps or higher is good for that clip. But switch to 24fps for normal video.
Note that others will have varying advice, and you are doing the right thing by asking for advice.