Personally, I'm inclined to use Kamala Harris' first name just because it's fun to say. It has a rhythm and repetition to it. Also, we've already had a President Harrison, so it distinguishes her.

With Hillary Rodham Clinton, I usually used her first name, initials, or full name to distinguish her from her husband. As much as I loath that she was always in his shadow, she was a force to be reckoned with. They may be a power couple, but she deserves her own recognition.

As for Tim Walz, Tim is just too common and uninteresting. Walz has character and it's close to waltz.