I picked up our first toilet seat lock from resale - it was a style I had looked at on Amazon, but couldn't decide. I figured for $2.50 (instead of $7) it was worth giving one a try. We decided to put it in downstairs in the half bath, but obviously have plans to procure for the other bathrooms too - once we know if this is a design we want to stick with.
Now that it is in place I hope one of my next posts isn't about me wetting myself because I failed to get into the lock fast enough after returning home. It's hard to use public facilities w/ the little one in tow - and sometimes you get home REALLY needing to go!