I found this thread on learning Giant Steps on guitar the other day. I got inspired to study it.
I considered choosing it from the graduate repertoire for my SDSU audition in February. The progression isn't difficult at all; there are only three keys. The only trick is that they often change in the middle of a bar. The real hurdle is the tempo. It's not the kind of tune that sits well at anything less than breakneck. While it's great to practice slowly, it's not impressive.
I eventually chose Moment's Notice for the audition, so I didn't get much past learning the head and changes for Giant Steps. I intend to now. Maybe I'll use it when I audition again in the fall.
I've started with practicing the following ideas over the progression. I play 1 2 3 5 on the first two beats of each bar, and 8 7 5 3 on the last two beats if it's a new chord, 7 6 5 3 if it's the same chord. This is helping a lot. Even though I have this entire exercise memorized in one position, I can visualize all the notes in the key as I pass through each one. My next step is to play this exercise all over the neck, incorporating slides and position changes. Then I'll look for new exercises, copping ideas from Coltrane's solo. Once I'm comfortable using a few different phrases over the whole progression, I'll start mixing, matching, altering. But I'm getting ahead of myself. For now, I'm focused on 1 2 3 5.