I've done the whole co-op and lots of extracurriculars thing, and it just doesn't fulfill my reasons for homeschooling. I homeschool for the rigorous academics, and I need to be at home, teaching my kids, in order for that rigor to happen.
Co-op and Park Day take up too much time--getting kids ready, travelling, being there, travelling home, getting the kids back on schedule (which rarely happens because I'm absolutely exhausted from having to keep track of four kids out of thirty in an unfamiliar environment).
I go to a lot of effort to draw up lesson plans that provide plenty of good reading choices, experiences, and activities. When I join up with a group, I find that my lesson plan has to be pushed to the side in order to accommodate the group, and the group has never risen to the level of my lesson plan.
I am a freakishly stressed-out woman on co-op or park days because we're trying to get everything done before we go. Why push the kids to finish up quickly to go to something that isn't as good as what they'd be missing at home, and I somewhat dread?
To be clear: The women in the co-op/Park Day--I love 'em. They are excellent women who take homeschooling and motherhood seriously and I admire how they run their families. I think I only stuck with the group for so long because I like the women so much. But the group takes away more than it provides, in the long run. It's just getting to the point where I have to choose "better" over "good"--and my lesson plan is better, despite how good our co-op can be. Each one of us homeschools for slightly different reasons, and I've yet to find another homeschooler in my area who is as focused on rigor and depth of academics as I am. I've actually been teased a fair amount for how much I expect of my kids, and some people think I'm flat-out killing off their "love of learning" because I insist on worksheets being completed and sloppy work re-done. I don't need that in my life. And, oh my goodness, I cannot handle another conversation about gluten-free, sugar-free or dairy-free lifestyles. I like McDonald's and I am at peace with the pleasure I get out of eating salty french fries.
As far as extra-curriculars, they fall into the same vein of thought--if they're not offering something better than I already have planned, we don't need 'em. I provide athletic opportunities, I teach art, we do crafts. I do farm out the piano lessons because I do not want to teach them. No need to torture myself. My kids have friends, we have church, I have my Knit Group...we have a full life, no need to add more.