200-300K/year (and higher) pensions are pretty much entirely executives who weren't union members, it has nothing to do with unions.
e.g., the #1 highest: http://articles.latimes.com/2010/dec/27/opinion/la-oe-cole-v...
"Denson also earned $407,908 in total wages in 2011, according to city data, making him the highest paid city worker in 2011. Of this sum, $212,738 consisted of "cash out" pay, which accounts for such factors as vacations, holidays and unused sick pay. His regular salary was $195,169."
All defined benefit pensions -- whether set by union contract or not -- use these kind of formulas. But the high pensions are not the product of the formula alone -- even if you work long enough at one of the formulas to get near (or over) 100%, you still aren't going to get 200-300K per year pension unless you have a last/highest/(average of last three)/etc. years salary (which ever is the base for the particular formula you have) high enough to push the pension that high.
Surprisingly enough, almost no rank-and-file workers have that kind of salary. The people with 200K and higher pensions are mostly people that are retiring from executive positions.