Good for you for seeing the beauty in your husband, your children, your friends, your job, your life. Good for you for wanting to share things that are lovely and positive and are gifts from God. Good for you for realizing that some things are best kept personal. To be clear, I am not a fan of fake people. I don't think anyone wants to see a friend post about her great marriage when we know, behind the scenes, it's miserable. I'm not saying that.
I am also not suggesting that everyone's life is a ray of sunshine. If you have a sick family member and are asking for good thoughts and prayers, I think that it is lovely that you are reaching out for support. In the same vein, if you have a challenge that you think your FB friends might have good advice for, do it. Who is isn't a fan of learn from other's experiences? And, yes, we all have bad commutes, days or weeks where FB might be a great place to vent. 
I am simply suggesting that we should go a little easy on those people who post positive things all the time. They are happy and they probably work hard making the choice each day to be happy. Don't knock them for that. Let them be happy and stop juding so much. 