I'm pretty well-read when it comes to Robert Johnson. I did a fifteen minute presentation on him for my Rock Music and Culture class (I know, but I needed to fill the back end of my schedule and I couldn't resist an A that easy). I did it without notes. I'd made some notes, but I never laid eyes on them even though they were right in front of me. That caused me to go off on a few tangents and forget to mention a few things, but no one seemed all that interested anyway. I have the complete recordings in front of me now.
You're missing, besides the tracks I already mentioned:
"I Believe I'll Dust My Broom"
--From the 11-23-36 San Antonio session, noted for providing the blueprint to Elmore James' career, the Dust My Broom lick shows up in well more than half of James' recordings.
"Sweet Home Chicago"
--From the 11-23-36 SA session, commonly played at the end of All Star blues concerts where everyone takes a turn.
"Phonograph Blues"
--Also from 11-23-36 SA session, has a safety take, though this isn't a tune that makes the complete recordings an important pickup.
"Walking Blues"
--From the 11-27-36 SA session, this is a tune that makes the complete recordings worth it. Very common delta piece that's the parent piece of many other delta songs. Has been recorded by everyone from Son House to Muddy Waters.
"I'm A Steady Rollin' Man"
--From the 6-19-37 Dallas session, a nice tune to have.
"Little Queen of Spades"
--From the 6-29-37 Dallas session, two takes, neither of which is all that spectacular.
"Malted Milk"
--From the 6-29-37 Dallas session, in the "Little Queen" strata of Johnson Tunes, no safety take.
"Drunken Hearted Man"
--From the 6-29-37 Dallas session, two takes, essentially a superior version of "Malted Milk" with different lyrics.
"Stop Breakin' Down"
--From the 6-29-37 Dallas session, two takes, covered by the Stones, good piece.
"Honeymoon Blues"
--From the 6-29-37 Dallas session, meh.
Out of those, "Dust My Broom," "Walking Blues," and "Steady Rollin' Man" are a must haves if you're a fan. And really, this music is essential for an understanding of American roots music. Sell the wife with that, and maybe she'll understand bringing home Leadbelly or Skip James, who I highly recommend. James' "Devil Got My Woman" is believed to be the parent piece of "Hellhound on My Trail," and he recorded a version of "22-20 Blues." I have the Yazoo cd The Complete Early Recordings of Skip James--1930. and it's quite excellent. Cream did a cover of "I'm So Glad," which is on this cd. I got the Robert Johnson complete recordings for under $15 at Zia and the James' recordings from Best Buy for around $9. The last time I was at Best Buy they had a James cd, but not this one. You could easily find them on the web, I expect.