I've been using Candelles candles for over a year and just (embarrassingly) discovered the tart wax melts they carry. There are some places in my home I can't use flames, and if you can't use candles either, wax tarts are a great alternative. Candelles uses their secret ingredients blending essential oils but more concentrated.
When I was looking at tart burners I was surprised how expensive they were. They range from $20 to $150. I have some mason jars, and a coffee/candle warmer and that has worked great.
Since it's more concentrated than the regular candle, the scent is stronger. I've used the Soft Cotton tart, I put it in my closet and underwear drawer, and even when not in use, it still leaves a faint scent. Get the wax tarts here.