Design your own program!
The wonderful part of teaching adults is their motivation. Grown-ups who take piano lessons want to learn!
As a general standard for adult students, I work with three teaching books from Alfred Publishers. These books move at a faster pace than the children’s books.
Of course, each student can add other books and styles as he or she wants. That's the pleasure of music! If you like, we can focus on popular, classical, jazz, Christmas, and/or all-time favorites.
Any adult student may drop any of the teaching books at any time. I let adult students make their own choices. However, I've found that it is more frustrating to advance your music skills without the help of these teaching books, which move along one level at a time.
I've spent considerable time analyzing and trying different books, and I strongly recommend these to ensure that every student accomplishes the fundamentals.