We even added a kitchen downstairs.

You can't do the kitchen and leave two old bathrooms.

A lot of homes have had bathroom and kitchen modifications without permits.

Walls come down, kitchens come out, and bathrooms get a major facelift.

They will be equipped to buy it.

It is definitely cheaper to do it while you are already working on kitchen and plumbing.

There are also requirements for receptacles in kitchens and baths. 

Any office that doesn't have this information goes for cost of equipment, which is basically probably a loss to the owner.

To prepare for maximizing bonus depreciation or conducting a cost segregation study, you can begin gathering detailed records of the property's assets and improvements, coordinate with a cost segregation specialist early, and consider any renovations or purchases of eligible equipment to align with tax strategies that take full advantage of the current bonus depreciation rates before they phase out.

Very dependent on each home's usage profile (as you mentioned) along with heating/cooling equipment type, utility rates and and solar net metering schemas.