If its in the budget I would look at stepping up to the Pro Cinema 800, bigger sub, larger drivers in the satelites. Also look at the PSB Alpha series, pretty decent entry level / quality speakers, but might take you above the $800 range. Another look might be a Mirage set up, however I have all Definitive in my home and am very happy.

As far as the Marantz I'm just a fan. Its pretty much all I've put in for the last few years and have been very happy. Nothing wrong with Denon, or look at Onkyo with their 608, very able receiver at the price point.