OK .. I'm after a bike for Audax and need suggestions

OK guys .... I need some advice

I'm looking for a bike that I will use as my daily commuter (on tar/asphalt roads and approx 250km /week just commuting), but I want a bike that I will use on some audax rides. (up to 600 Km)

I already have 2 bikes (my 'fast bike' is a Giant TCR which I have...