Right now doing a Tuscan theme is very popular, try using deep shades of yellows and reds. Comfortable chairs and wine themed accents. While the rooms are attached and flow together it is not necessary for them to be the same.
You would probably want the rooms to flow together, so pick colors that will complement each other. Don't decorate the kitchen with flowers and then the family room with ducks. Keep the theme an even flow.
To separate the two rooms you can paint the kitchen one color and the family room area another. Decorate each with their own separate themes to show separate areas.
