After firing some really ****-poor framers, I am facing the reality of two rooms with really unlevel cielings. All the joists drop in the same direction by anywhere from 1/2" to 1.5".

Is there a novel solution to this that I am missing? So far, the choices I know of are:

a. cut thin rip strips to finish-nail into each joist (very time consuming and high skill required)

b. Remove all the blocking and nail in 2x4s next to each joist, dropping the whole ceiling 1.5-2".

If anyone knows of a simple system developed for these situations or a way to do this I haven't thought of, PLEASE let me know ASAP.

Apply 1" x 3" straping every 16" across the room.........

Leveling them to a string line set at the LOWest point+strap ........

use shims or blocks and long screws to secure to the joists......

Will the crown/dip affect a floor upstairs?

I agree. 1x3 strips 90º to the existing joist. You can level each one with spacers or shims at each joist.