For me, the ability to really play and solo over changes well is knowing the melody. I have a huge pool of standards that I play and am going back and learning the melodies .. I'm up to about 100 that I can pull out of my head .. the goal is about 400. I get about 4 a week going then mix them into the rotation to keep 'em fresh. Lot's of work, but it really has paid off in many many many ways.
Here's a few I really dig:
Anthropology
Whims of Chambers
How High the Moon
I Remember Clifford
'Round Midnight
I suggest just going through the real book from beginning to end, skipping ones that are just impossible. It's great reading exercise, and sven's right about the importance of melodies.
Agree. Thus the phrase; "Let the melody be your guide."
I play Country in two bands, our gig book in one has over 250 songs. The other is a new band and already has over 100 selections. So yes, look through several real books and pick the ones you consider "must know" songs.