Watch the Rhythm Changes Forever online guitar lesson by John Goldsby from Upright Bass Handbook
All of the notes here are in either the half or first position. Make sure you have the notes under your fingers and know where you need to shift in and out of first and half position.
This 32-bar chorus of rhythm changes uses typical chord changes, but you might notice that there are some variations in the between the first, second, and last A section. Jazz players don't always stick with the same set of changes through many choruses of "Rhythm Changes," and this gives you a taste of a few of the common variations.
The B section (or "bridge") is a progression in the "Circle of Fifths" or "Cycle of Fifths": D7, G7, C7, F7. Note that in the last two bars of the B section, we play Cmin7 to F7, instead of just staying on F7 for two bars. This is a typical way to turn a dominant 7th chord, in this case F7, into a "ii-V7" progression like the Cmin7 to F7 we hear here.
Although "Rhythm Changes" contains a lot of chords--often two chords per bar--the same concept applies to creating good walking basslines: Put the root of the chord on the downbeat, and lead into the next root with either a chord tone, scale tone, or chromatic leading tone.