Your doubling the salary for teachers due to tenure is questionable. The reason tenured professors don't quit is only partly due to tenure, also due to the fact that they find being a professor more interesting than the other work. Regular (grade-school to high-school) teachers don't exactly have tenure (though for those in most unions it is close), and they probably don't have the same employment options outside the profession.

I'd give a multiple of 1.2.

Most teachers are not professors. Most teachers work for public schools in the k-12 arena. Many times tenure doesnt work out.

Teachers rarely get overtime, but overtime is necessary. The best teachers I know, and I know about 20, work 7-7. They work during the summer to setup curriculum, to tutor summer school students, to select books, to setup their classroom. And they do this all without any extra pay than their salary. They also supplement poor school budgets with their own money to buy supplies the students need to learn.

They are generally pressured to pay into a Teachers union that supports the misfits in their profession, and doesn't generally help them at all. These same awesome teachers are paid solely on the number of years they have been working -- not (at all) by performance, skill, or student/parent reviews. This translates into little reward for awesome teachers over not to awesome 8:15-3pm teachers.

But I digress.