Get Out of the Bathroom, Please

Okay, so we have 6 children and 4 bathrooms (3 with bathtubs/showers).  So in my mind this should not be a problem.  But there is a something very troublesome going on in my home, in particular my bathroom!!!  Why, with this many tubs and showers and toilets and mirrors and electrical outlets, is my bathroom the only one deemed suitable for everyone's use? And I mean everyone! It would not be so bad, but the problem is compounded by the fact that few if any of the kids actually pick up after themselves.  Instead my bathroom generally looks like a tornado (no, make that a hurricane, because of all the puddles ) just went through it.  Dirty clothes and socks and underwear, not to mention towels that are NEVER reused all over the floor and countertops!   The problem was so bad a few months ago that I posted a DEAR CHILDREN sign on the bathroom door requesting that it only be used in dire emergencies.  It was not so politely ignored.  There is hot, running water in the other lavatories so what's so great about mine?  Yes the bathroom is bigger, as are the shower and tub, but these children are normal size.  They don't generally require extra space.  I often tell them sad stories of how I grew up in a one bathroom home -a small bathroom at that!  But they haven't any appreciation for what I am talking about.  We have talked about getting a new lock with a key (did I mention that they can pick the lock?)  But what if we lose the key.  This could be a big problem for me. I've lost lots of keys in my lifetime.  And do I really want to get locked out of my own bathroom when I really have to go???   I know, I should never have let them use my bathroom in the first place.  But I never realized I was creating such moochers.  At this point all that's left to do is leave them with a mother's curse: "One day when you have children of your own, you'll have this lovely bathroom or car or piece of furniture or whatever it is that you hold dear and then you'll have kids just like you."  We all know how it ends.  I just don't understand it.  It's just one of many pet peeves.  Like, why does someone have to be told (husbands included) that the sink is overflowing with dirty dishes and this problem can be solved by emptying the dishwasher?   Why do my kids never ever get to bed on time? Does it have something to do with the fact that I am never on time for anything else?  But even once they're in their rooms, why does sleep elude them?   So many questions, but never enough in the way of answers.   Oh well, gotta love 'em, bathroom wreckers or not!