How to have a gorgeous smelling house.

[Socrates73]

Any tips much appreciated!
My house downstairs is all open plan with unfortunately nowhere to put the cat's litter tray except tucked into a corner of the kitchen. He won't use a coveted litter tray and will go on beds/sofa instead if I don't leave an open tray. Although I keep this very clean I'm conscious that my house always smells vaguely catty. I'd love to have one of those houses that people walk into and just think " mmm nice smell"
If you have a delicious smelling house, how do you achieve it?
I go through air freshener like it's going out of fashion but it doesn't achieve the result I'm looking for.
Thank you.

People suggesting outside or covered tray. Yes he does go outside quite a bit but as we can't fit a cat flap he is reliant on me opening the door for him or leaving him outside. He won't tolerate a covered tray, he's a rescue cat with a traumatic early life. It's taken me six year to get him reliably using that particular litter tray in that spot..... so I'm going to have to stick with that and work around the smells activated charcoal sounds interesting!

Polecat it gets changed as soon as he does anything but yes, there really isn't another workable option.
Trust me it's better than where the cat used to do his business

I use reed diffusers (and like another poster suggested, I try to buy ones slightly more expensive as the cheap ones are never as good), but I swear by zoflora and use a steam cleaner with a capful of zoflora in it every day which keeps the house smelling lovely.