Trudging slowly over wet sand...
Sundays from my childhood were invariably headache days. The combination of getting up early, having only one big meal, and being cooped up in the house always gave me a headache. My parents never let us play outside on Sundays (with all of the other Mormon kids), so my siblings and I always associated Sunday with being miserable and stuck in a stuffy house playing game after game of Mastermind.
Like Kaycee, when I went inactive, I was amazed by this entirely new day that lay before me, ripe with possibilities: Saturday II. Instantaneously, my weekend doubled. That's tough to compete with. It'll be years before we're able to squeeze another day off into the week.
When trying to decide what feels right to do on Sundays, I think it's important to look back on the origin of Sabbath observance. The Sabbath was instituted after the Israelites were freed from bondage in Egypt. They went from having to work seven days a week (being slaves and all) to having a rest day. In fact, not only did they not have to work, they were prohibited from working on pain of death. As we can see, it was a pretty sweet deal for them. All they had to do on their day off was to remember who freed them from the Egyptians.
Think of how great those first Sabbaths must have been for the Israelites; the only time that came close for me was those first couple of Sundays with limitless possibilities. I think every Sunday should be more like that: a day of joy, feeling happy to be alive. I don't think we're doing the Lord any favors by dedicating a miserable day to him. I know this point often gets obscured in church, but God actually wants us to be happy. It's silly and counter-productive in my opinion to wear our suffering like a badge to prove how dedicated we are. Go out, have fun. Drive around. See a movie. (Trust me, no matter how many Mormons there are, the movies will always be open on Sunday. You're not making the projectionist work any more than s/he'd already have to.) Enjoy your free time, and thank God you're not making bricks for some guy in a silly headdress. That's what the Sabbath was originally about.
Whatever you do, don't force your kids to stay inside and play board games in their Sunday clothes. LET MY PEOPLE GO!