My apologies in advance for those more technically inclined... but this was an eye opener for me.
Decided to call Apple Tech support for my router before blaming the Panasonic 220 any more; and glad i did. Looks like my 2.4 ghz channel was over-run with interference from neighbor's networks, and switching the channel made a huge difference. Very odd that my signal strength still read 5 full bars despite the interference.. but it appears ok now. Will wait to see how it performs the next few days, but this seems like the right fix.
For those experiencing problems, I advise you switch up the router channels (or call tech support if available) before returning a unit due to poor Viera connect performance. Apparently it can show full connectivity even though throughput is severely constrained.