Ok, me and DH are obssessed with our house smelling nice. These are the things we do:
Open windows/doors when possible as much as possible.
Oil burners: really cheap from B&M ffor 99p each, I have two, one in the kitchen/dining area and one in living room. DD (2) is well trained not to touch or go near it. We buy bumper packs of tealights cheaply from asda or pound shop, and burn all sorts of oils and fragrances in there and it lasts all day.
Reed diffuser: Ive got one of these in my living room, an air wick one, and it smells gorgeous.
Scented candles in the bathroom and bedroom and living room. And dining room.
Plug ins in hallways. (the one with three in it, forgotten which brand it is now)
Fragranced Vacuum cleaner discs : you can buy these for a quid or so from asda too, and they smell lovely every time you vacuum.
A cut lemon in the fridge does the trick to keep the fridge smelling nice.
And I use the highly concentrated Zoflora disinfectant whenever I mop hard surfaces (just afew drops in boiling water) and it smells good for ages.
Hope that helps.