I think taking care of your family on Sunday, whether it be food preparation/cooking, grocery shopping, etc. is Godly because it is doing the work God has set before us. On the other hand, I do feel it best to do such things on another day if at all possible.
For biblical referrence, Matthew 12:11, And he said unto them, What man shall there be among you, that shall have one sheep, and if it fall into a pit on the sabbath day, will he not lay hold on it, and lift it out?
I take this to mean as I stated above, that certain times, things will fall out of order that need to be immediately put back into order, on the Sabbath. God understands that, and has made clear that it's okay, don't leave the sheep in the pit..that wouldn't be good stewardship! Now, there is no way a sheep is going to fall into a pit on a weekly basis, so I do not feel we should make habit of cooking/shopping/etc. on the Sabbath, but there are times we should take care of things on the Sabbath BECAUSE God wants us to. Common sense should tell us when it's okay, and when we're stretching it IMO. I also do not think we should be judgemental of others who do things on the Sabbath, simply because we don't know their personal situations.