If it makes you feel better, when I read your post I thought maybe I wrote it and forgot...I also have a non sporty DS who is 11 and weekends can be tough. My DS is a smart, very happy kid, and he has a nice small group of friends, but he's not a kid with a million friends, no kids in the neighborhood to play with for him, etc. He does three weekend activities, religious school, instrument lesson and tennis, but still lots of time left. Sometimes he and his younger sister play well for hours, but she often has more parties and play dates.
We definitely do family outings - hikes, festivals, movies, sporting events, etc...but there are days like today when we really didn't have much on the calendar, DH and I needed some time around the house to get things done and run a few errands and DS was bored, too much electronics, although he did read and play outside some and did a little homework. I'm not sure what the answer is / / I don't want to put him in more organized activities because it makes it hard to do family outings, but DH and I work so not every weekend day can be wall to wall fun activities.