I've never been a fan of the peacoat really, but the colour is nice and almost anything will go with it.
Your idea of navy with tan shoes is absolutely sound and will create a good balance of dark and light tones. I think stone/camel coloured coats work best with dark colours to anchor them so your current wardrobe would be ideal.
How about these for ideas:
Simple and stylish: a black roll neck, black jeans and black chelsea boots (I think that would look awesome)
Autumnal: cream/ecru cable knit jumper, dark brown tweed trousers and tan brogues
A Splash of colour: dark chambray/denim shirt, dark red skinny chinos/cords and tan brogue boots