acqua di parma room spray when it goes in the new yr sale.
I have an assortment of beautiful aromatics in my tea/coffee cupboard so that when you open the door you get delicious wafts. I change them around. I've had: bashed coffeebeans in a little open dish, bashed cardamom pods, sprig of lavender, different herbal teabags, little pieces of vanilla pod, a tiny dish of cinnamon or cloves... The smell of my tea cupboard makes me so happy and is one of the things I miss most when I'm away from home.
In a bathroom I don't think there is any nicer smell than bleach. Not over the top OCD bleach that stings your eyes, just a gentle reassuring whiff.
Lavender is beautiful for bedrooms, or a sensual-smelling candle for evenings. You used to be able to get a truly beautiful amber one in selfridges floristy bit, but I can't find it anymore, and I haven't found another as nice, although space nk ones are lovely, and do go in the new yr sale.
A good leather cleaner smells nice in living rooms (though obvs a little weird if your furniture is fabric!)
Any essential oils on a damp flannel on radiators work nicely, and those lightbulb rings are clever if you can find a nice oil - easier said than done IMO.