OK, I've spent pretty much all day on this, and I've narrowed it down to the following:
Used Onkyo TX-NR709 (it has direct iPod connection via USB, bass management, room correction, fully networked, and seems to have corrected significant QC issues with the 708); and
New Polk PS (12-inch powered subwoofer); or
Used Emotiva Ultra 12 (powered sub)
I came close to choosing the Marantz SR-6005, but decided that (all other things apparently being equal) I might as well get the network connectivity.
Comments? Thanks!