re: Best step ladder height for home use?

My rule of thumb is this:

With 8 ft. ceilings, use a 6 ft. ladder.

With 10-12 ft. ceilings, use an 8 ft. ladder and adjust accordingly if ceiling height goes up.

I like to be about 3 rungs shy of the top of the ladder to work overhead for a safer stance on the ladder. Plus, if using the fiberglass ladders, the top of the ladder usually has a tray type configuration to hold small things like wire nuts, screws, etc. and places to drop screwdrivers through the top to keep them from falling to the floor.