Many jazz takes on Someday, like from Oscar Peterson and Wynton Kelly actually change the tune to 4/4, but Bill Evans swing it here in 3. And in doing that, he leans heavily on 4 different rhythmic feels.
The Traditional
The traditional classical waltz is played as "oom-pah-pah." Bill uses this explicitly a few times, but mostly as a hint, or throwback, to the tradition.
The Swing
This is still pretty true to the tradition, but shifting the 2 chord "pah's" up half a beat each so they are syncopated. The strong downbeat on beat 1 is still typically played by the bass player or left hand.
The Two-Feel
This one takes my students back at first, playing a waltz with only 2 beats? But, its probably the most important of the four examples.
The rhythm is two dotted half notes, which evenly divide the 3 beats into 2.
The melody is still felt in 3 beats much of the time. In that case, this two-feel rhythm is a counter rhythm against the melody, which is super cool.
We often shift between the swing feel throughout the song. This helps keep the 3-feel in your head when the rhythm shifts.
Here's an example of me playing a combination of all 3 of these:
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Waltz in Four
Bill uses this one a lot. It looks pretty hard when you try to read it in notation. But, in reality, its pretty easy to feel.
We're basically taking the two feel above, and further dividing those 2 beats into four. We change the notation to a tuplet to make it easier to read, but it's really just 4 even beats in the measure. (the drums keep going in 3)
In the Bill Evan's recording above, listen to the descending line in the intro at 0:07 to hear a really clear example.
Download a PDF worksheet of the rhythms: Jazz Waltz Rhythms.pdf