The Kinks- the stuff you listed is mainly what I stick to (well, not "Hillbillies"- never liked that one) but you at least need a comp of the pre-"Face To Face" stuff. I recommend getting both the Rhino "Greatest Hits" and maybe one of the various 2-disc career overviews as well. Also heard the BBC sessions (lots of good songs covered but the sound quality or performance isn't good enough for me to really call it essential). Have also heard "Everybody's In Show-Biz" and "Preservation 1". Ray's writing keeps them from being unlistenable but they're forgettable and embarrassingly corny.
The Who- You haven't heard "Live At Leeds"? Best rectify that ASAP. Do the 14 track version. And "The Kids Are Alright" is a killer live career overview. Also, don't listen to the others- "A Quick One" is the main studio album you're missing, though I'll also stress the importance of "Meaty Beaty" (or "The Ultimate Collection", which is basically an expanded version)
The Byrds- sounds like you've heard everything worth hearing- and more!
Wilco- never really gave this band much of a chance- what little I've heard bores me to tears.
The Feelies- "Rhythms" is good for what it is but I always kinda assumed they were a 1-album wonder.
Gentle Giant- Aren't those last 3 albums supposed to be awful? "The Power & The Glory" is the main album of theirs I never got around to and I'm sorta curious about their BBC sessions as well but TBH I don't really listen to them very often these days