With an upscaling TV, the only advantage I see to using the upconversion/switching of an AV receiver is if you have too few digital inputs for yuor needs (XBox, Playstation, DVD player, digital cable or dish, etc) and/or only want to run one line to the TV. Out of curiosity, are you considering a universal player (CD/SACD/DVD/DVD-Audio)?
Bryan...you've got quite a few options...