CIM,
Just getting back to your original question about how late you would/could accept a landing clearance.
Depends what you are flying - in a "simple" single, lower than in an assymetric complex multi.
How much height does your aircraft lose "cleaning-up" and climbing away?
Then add some to that for reaction-time, less than perfect performance, higher temperature/altitude etc.
This sort of 'decision height' (AKA commital height) you need to have in mind all the way down final approach if you haven't already been cleared for the landing.
I don't think there's one answer suits all
