I'd configure it as a 1 bedroom with an open floor plan to allow for a spacious-feeling office area.My wife and I are considering buying into a situation like that in upstate New York or Connecticut- we like the idea of an accessory dwelling unit where we could go to conduct business(she's in interior design, I'm in real estate primarily.)

UPDATE: After doing some more research there is something called an ADU (Accessory Dwelling Unit) that should allow us to do this 2 unit strategy. 

Thanks, StephanieAccording to one of the local Homestyle lenders, an accessory dwelling unit aka ADU aka guest house does NOT qualify as a one unit dwelling if the home is an investment property.

Also you probably want to work with an architect who has ADU experience I can recommend one if you want.Here is a recent article with more information: http://www.sfexaminer.com/city-easing-onerous-approval-process-accessory-dwelling-units/

They started allowing accessory dwelling units for owner occupants and have been trying to open up more areas for MF. 

She is not selling accessories, she is renting a home to actual humans.If you are treating your tenants like they are nothing and they don't matter, don't complain when they don't pay or not care about your house at all. 

Hi, Planning to build an ADU (Accessory dwelling unit) in the back, On top of my garage.

Therefore a two or three bedroom property cannot rent more than one bedroom at a time.The rental portion of the residence must be designated as an accessory use space.Must include the registration number in all advertisements.

Single family residence in Los Angeles (built in 1962) has only 1 covered parking spot, and a second cannot be added.Do I have to comply with current parking requirements (2 spots) to add a detached accessory structure for storage etc. 

No. its a SFH with an accessory dwelling unit.