As has been said, there are various options. When I retired, the max was 80% of the average of the highest 3 years' gross (including payments for extracurriculars like coaching). And no state income tax on pension payments.
I retired with an average gross in the high $90Ks. I took an option that pays about 73%, but continues reduced payments for my wife if I predecease her.
Also, I was paying 11% of my pretax income into the retirement fund (up from 7% when I started teaching), so it's not a free lunch.