Here's what I did to my TOTB quilt.
First I quilted all the black lines. Decided it still left too much space unquilted so I went back and added the lines shown by the red arrows. I was using black thread and didn't want the quilting in the very center of each block so I was 'jumping' over the little colored squares. I was very happy with the way it all turned out.

Very nice

I haven't read through all the in-put .... so I hope this doesn't bog-down your process:

Just a suggestion: Don't start marking on the quilt top itself until you are sure of what you want.... I've been there, done that, and regretted all the confusing markings by the time I got what I wanted.... long message here, but stick with me ....

A few years ago, our storm-door got ripped out of shape by a terrible wind storm: husband replaced our storm door ... I kept the old door (for why???? Who knows!!) Two years later I finally found a use for it....

I recently was having your trouble plotting out a quilting idea for a veeeery special grandma-to-be's gift quilt .... and I didn't want to start marking up the top until I was SURE what I wanted ..... AHAAA! Plan B

I took apart that old storm door ...saved the two metal- trimmed glass parts ... threw the rest in the recycle bins .....

I cleaned them up and used them to place over my quilt top (laid out on the carpet) and then used dry-erase pens /crayons to plot out my hand quilting pattern ....

My first-plan try was a bust ... I tried at least three or more different configurations/combinations .... but I finally got exactly what I wanted ..... and it was nothing like my original thoughts -- Just playing around, many ideas evolved .... marking on the glass freed me up to NOT be afraid to experiment, to move from the expected to something more unique since everything was "temporary" anyway..... I found gaps where I needed to cross-hatch, and some spots that needed softened with arcs and swirls ..... some spots I traced around large cookie-cutters to make a certain inside-joke statement .....

'Twas better making mistakes on the glass panes than on the quilt top itself....

I found that using just one huge glass pane at one corner of the quilt gave me a good idea of what I was working with, but since I wanted different things in different quadrants I was able to move from section to section and work it out .....

Sorry I don't have digital camera capabilities, or I would show you what I mean..... The quilt turned out lovely; I was pleased; and grandma-to-be was impressed....

Now I look forward to that part of the process .... instead of saying "what was I thinking?" .... I just don't think to hard at that point any more .... I just doodle ...... and things flow ....

Have fun .... the total journey in quilting is fun all the way. The marking-for-quilting is just another fun step along the way.

Your quilt is already a beauty .... and it will only get better and better .... hang in there ... Play with it ...... and don't let it become a UFO ....

Sorry, can't help with quilting ideas but I must say how delicious your colors are!

Stitch in the ditch is done in/on the seam. Straight stitching can be done at what ever widths from the seam you want (1/4", 1/2", etc.)

Was just going to say the same thing. Glad I read through all of the posts so I wouldn't sound redundant.

Instead of the regular SID I prefer the look of doing my stitching 1/4" to each side of the ditch. I like this look alot. Plus the fact I have a hard time staying in the ditch makes it my kind of quilting. Glenda

Swirls are easy. I still can't master a good circle but overall swirls are fairly easy for me.

i would stitch in the ditch or get a varigated thread and do echo stitching
love your quilt

OK....lets go back and read the original post. I undrstand it must be quilted with the walking foot as Cowgirl does not do free motion. So that slets the style. With walking foot it must be straight lines or curves that you can manulipate with the walking foot (feathers and leaves unless very large would be difficult to do). If circles then they must be very large so the walking foot will travel around.
"Outside the Block", for me, eliminates SID or 1/4" outside the seam. Diagonals and squares are also out. If my spider web is weird then think about a block design that would cover the entire 40" square rather than individual blocks being quilted. A large single pin wheel pattern would meet this definitation in my opinion with lines along side it to cover the areas.
Straight lines from side to side forming a star would meet the requirements. Since there appears to be very specific instructions about how to quilt it (not design) then they should be followed.