Fortunately for us most of that crowd is into crypto currencies these days. 

Homes are easily well above $700k and don't expect privacy at that pricepoint. 

Even if it is zoned for single family homes, you might be able to build it and rent it on Airbnb for WAY more then just an apartment and you get the added bonus of a guesthouse on your property without the loss of privacy with having someone in the apartment all the time.  

You definitely give up on a few things - complete privacy (multi-families are old, with thin walls and creaky floors), sharing a backyard (we never felt comfortable having friends over and having too many beers on weekends or holidays), and we were always in landlord mode mentally (let us know if you need anything!

The kitchen and bath are different, and my side has a fenced-in privacy yard and off-street parking.

House hacking would never be an option, her privacy is too important

If you want to splurge and add a patio cover, that’s a nice touch, but it’s not cheap.Privacy: Make sure to create separation and privacy between the main home and ADU by constructing solid fencing in the appropriate location.

unless you have a change in circumstance -meaning a need to move due to closer to work, bigger home for family, closer to school, privacy to a SFR 1 unit.Unless you own a home and buy the home as a second home going traditional and you can rent it out right away as an STR/AIRBNB. 

My idea was going to be to add a partition wall to split the garage so each tenant had the own side as well as added privacy / protection.

The prior owner put the sink in "for women, so that way they have their own privacy compared to the shared bathroom"...