Oh man, I've always wanted one of those. I'm thinking a Duramax for power, tuned and built for around 800hp. Airbags all around, 20s up front with 22s in the rear, a full leather interior with walnut wood accents, nothing RADICAL, but just a comfortable people hauler. A good theater system inside, with wireless of course, and plenty of slide out racks in the rear area for easy luggage and baggage storage, plus the roof rack.
And I'd repaint it, but in a darker brown.