I have a friend who always lights a candle in the bathroom when guests come over. It's a charming little detail, yes, but they're far more confident that their house isn't going to burn down than I am. My advice: don't leave your candles unattended for longer than a few moments, seriously.
Instead, I have a bit of a ritual, specifically around making sure my bathroom smells good (all the time, yes, but it gets kicked into overdrive when we're hosting). That includes home fragrances and natural, but beautiful-smelling cleaning products, but there are some smells that you're only masking by filling your bathroom with nicely-fragranced things, and without tackling the problem, you won't have a truly fabulous-smelling bathroom.
