I sometimes have a small store as part of a community lot, but not categorized as retail, and not owned by anyone technically, so I guess that is not very interesting ;)
My retail businesses are mostly built as small shopping malls, meaning there is a variety of stores, and the malls can look quite different, from the typical city shopping center to a more rustic and old fashioned bazar. I normally don't play these actively, but build them for my sims to go shopping somewhere. There might some going there to sell stuff from their own sales table, too.