An Argyll jacket with a waistcoat is very versitile, and the waistcoat will do away with the need for a belt all together.

Tweed sport coats and kilt jackets are generally considered to be more on the "casual"/"country gent" side; Whilst I love tweed, for a more versitile jacket, I would go with a charcoal grey/black colour, which would go with just about anything.

T.