OK, further checking in the TV's settings indicates there's a way to get constant link via ARC for TV by going to the Viera Link Settings page in the Sertup menu and setting the default speakers to Home Theater. The tradeoff is the TV wants to always turn on/off the receiver when it's turned on/off, and the TV resets to Standard vs the Game mode I prefer. Since there's often times earlier in the day I just want to surf the net without any sound, I prefer the TV not to turn on the receiver.
Panasonic and Yamaha both say this is normal and it varies with brand and model. My workaround, since I don't want the receiver turning on when I don't want it to or resetting video modes, is to wait until the time of day when I engage in TV watching, then access the quick setup page for Viera Link via the Viera Link button on the remote, and navigate down one click to Speaker Output, and one click sideways to set it to Home Theater. It's quick, only has to be done once a day, and avoids unnecessary powering on and off of the receiver.
When only the Viera Link button is used vs the Menu>Setup>Viera Link Settings, it does not control the receiver being turned on and off and reverts to TV as Speaker Output when the TV or receiver are shut off. It's the difference between one being merely a Speaker Output setting, and the other being the Default Speakers setting.
Hope this helps anyone having Viera Link issues. CEC is not as "smart" in my case as I'd like it to be, but at least there's a fairly easy workaround for it.