Update:
Thanks to your help, we've got a good resolution here for all. After sharing Jerry's comment with her over the phone, the homeowner now accepts the value of re-finishing her kitchen floors, so we're going ahead with that plan. We're also writing her a change order to exclude re-finishing the adjacent dining room, and instead adding a perpendicular transition in the 36" doorway. All of the talk about sanding levels and visuals helped her to realize that this solution would be the best choice for her values and budget. She's happy. Subs are happy. We're happy.
Thanks again, and I'm looking forward to continuing to prowl this board for all your insights.
Kathie