Had a little experiment with this - if I built it as a community lot and put apartment things in, it couldn't have people live in the upstairs rooms. If I built it as a residential lot, a lot of the downstairs stuff vanished (mostly the pretty tat that I put on display in the consignment store).
I've in the end decided to change my idea and go for a bookstore / consignment store combined, but would still be curious to see if anyone managed to get a community lot like the consignment store working on the same lot as a residential area.