I have oak floor, cream sofas, cream walls and cream curtains with a small turquoise flower on in my lounge and have gone for teal coloured cushions and a teal and cream rug. Though I say so myself as shouldn't, it looks lovely.
With such neutral colours, you could go for any colour. Aubergine looks nice with taupe or any purpley colour. Or to brighten things up a bit what about fuschia?
I have tan leather sofas in our garden room and have gone for orange and brown cushions.