Like you, I have also been able to provide my parents with a home-- My personal house has a full live in basement with full kitchen, dining room, living room, master/master bath and half bathroom with a separate entrance. 

Denver homes commonly have a separate entrance to the basement, so that is the form ours took. 

Multifamily class A or B is more predictable, especially those with garages and exterior entrances as they feel more like a home and you have lower tenant turnover.

The basement (rare in San Diego - it is positions on a sloped canyon rim) is completely finished with a walk out entrance and compliant (I think) windows.

The property has 4 separate entrances and essentially 3 separate living spaces with relatively minimal work required; couple inside doors, add cabinets, sink and stove to complete a mother in-law. 

The casita will have a full kitchen, bath, hvac and it's own entrance.

Sight line distances between road entrances?

We make it very clear that each group will have their own private entrance etc. but we have had some success with this strategy. 

He also wants to install 3 entrance signs to parking lot (there are 3 entrances) and 8 info signs.

We are looking at a 24 unit class C apartment community, but the main entrance driveway, the main front grassy area with the signage and half of a back driveway are owned by another entity.