I like the FlyLady’s “Swish and Swipe”, where she makes it a point to use every bathroom every day, and to wipe down the surfaces and run a toilet brush around the inside of the bowl every day. It does work.
Looking down the road, though, I would suggest this: teach your kids that for a polite person, looking at the state in which they are leaving the bathroom before actually leaving it is part of using it. Make these questions about being thoughtful to the next person part of toilet training: Is the seat down? Is there toilet paper for the next person and an extra roll out? Is the sink presentable, or are there globs of toothpaste left on it? Did I slop up the faucet? Did I leave the medicine cabinet open, the box of bandaids out, and the wrapper to my new bandaid on the counter? Is the towel OK, or does it need changing? Is there at least one extra bathtowel and one extra handtowel in the cupboard? Is the water off all of the way? In other words, without worrying about whether I’m cleaning up my own mess or someone else’s, will the person using this room after me know I was thinking of them? Not in a nagging way, but in a positive “welcome all as Christ” kind of way. If a job needs chemicals or some other attention that only you can give, the kids can just give you or their dad a heads-up. If you walk by and it is a mess, just grab the first kid you see and say, “Sally, the bathroom needs seeing to. Do your best, and we’ll look over how you did in about ten or fifteen minutes.” (If you know Sally left it that way, skip over that. Do not make this about whose fault it is, but about having the habit of noticing the condition of the bathroom. You need your kids to get the habit of tidying when they see a mess, not looking for someone to blame when they see one.)
You will have to make sure there are always rags for the kids to use to attend to their messes, that kind of thing, but you will never regret having taken the time to do this.
Oh, and time how long this takes. It is literally a one to two minute job. It is pretty hard for a kid to complain to a mom who works all day about a job that literally takes two minutes.