I realized, on the way home, as I was reciting to myself "Don't forget the highlights on the rim and in the coffee, and be sure to put in the shadow cast by the cup into the saucer" that my age has caught up with me—someone 15 years younger would have thought immediately of snapping a photo with their cell phone to get those details for later, while I tend to completely forget I have that option. So I was doomed to painting from memory (which also isn't the greatest, the older you get, ironically!).
I looked at the contour and thought, "Maybe I should try painting this on another page, without the drawing, so it fits with the 30x30 challenge," so that's what I did first. I wanted it to be a real Liz Steel partly-there-and-partly-not masterpiece, but didn't come close to accomplishing that. There were some parts I liked and some parts that were total fail (such as the misshapen saucer!), and many parts that I'm sure could have been better, had I had that reference photo on hand!
Afterwards, I went ahead and painted the contour drawing version too, just so I could see the differences. I made some slightly different color choices for shadows etc. There are parts I like better about each, and of course I am not satisfied with either one! But it was an interesting experiment. I find that I do like delineating edges and shadows without benefit of drawn lines, but I also like the quirkiness and personality that the contour line brings. I guess I'll keep working in both modes and see what shakes out!