I wonder if it is okay to disconnect all of the knob and tube from the panel but leave the dead wiring inside the walls. 

A related question is this:The reason the roof panels may be/are soggy is because of rain leaks during a recent storm.

These solutions would have to pay off within 2-years (the typical holding period of the buildings in the portfolio) so something like installing solar panels wouldn't fit the bill.

Does that quote of $9K ($4500/side) include new breaker panels?  

So far have replaced drop ceilings and wood paneling with smooth painted surfaces, replaced brass fixtures and hardware with brushed nickel, installed high efficiency toilets and shower heads.

Breece Veneer & Panel Co., 232 F .2d 319.

Most notably old paneling (the real wood kind, not the cheap thin kind) in what will be a bedroom, and the old, possibly asbestos, ceiling tiles in each room.My current thoughts are to drywall over two out of the three walls in the bedroom (a new wall will be installed on the fourth wall for creating a new 3/4 hallway bath) and leave one wall with the paneling to paint over and act as an accent wall.

We’d like to take down some walls, replace wood paneling, and change out the linoleum for composite planks.

They had a gas generator running inside because the landlord was arguing with them about who was responsible for the repairs to the very old shorted out electrical panel.

Take away all of the “big stuff” like plumbing, electric, HVAC, roof, etc. and there are still plenty of 70’s buildings out there with original kitchens, groovy faux wood paneling, popcorn ceilings, really small closets, etc.