Good old Martha taught us that rather than buying those ridiculously expensive anti-slip mats for a rug, just turn it over and run a few lines of acrylic-latex caulk every 6 inches or so. Let dry and flip over and your rug wont be going anywhere!
I started doing this and will never stop! My tub & shower are always spotless-so simple. Simple shower and tub cleaner: fill wand half and half. Wet surface and scrub. wow! leave in shower & wash while you are already in there