One album I think is particularly intriguing is Shine, released 2007, I'm not sure if this is true, but is apparently her seventeenth and 'final studio album'! I've only listened to the first track to this so far but sounds good!
Blue was the first album I heard of Joni, so many good songs on that... Carey, River, Little Green, A Case of You of course you mention... was starting to play the guitar at the time, was about 7 years ago, and managed to play the first part of A Case of You...certainly opened my eyes to the realm of 'open tuning'! (which is where you basically tune the guitar in an alternative way than normal)
Court And Spark is definitely one to check out soon, I have it downloaded actually though haven't gotten around to fully appreciating it, will do that soon now.
p.s. When you said about having Hejira on while doing the chores, it made me think of Cat Power saying the exact same thing about Bob Dylan's album 'Another Side of Bob Dylan'! i.e. she only started to appreciate it when she put it on while doing chores, so it kind of permeated. I have to look out where I saw that interview because I'm pretty sure she said something about having it on repeat too! How strange...