Where do you want to retire? If I had to venture a guess, I’d say not suburban Florida. If you’re like the growing number of Baby Boomer retirees, you want to be in a city, close to public transportation, and near amenities like grocery stores. Armstrong Senior Housing, a new complex designed by David Baker + Partners in San Francisco’s Bayview district, offers all that and then some, with four levels of affordable senior apartments atop ground-level retail, a community center, and a library.