COLUMBUS—Many big cities across the US have reinvented their downtowns. Instead of being merely places to work during the daytime, downtowns now attract residents, shoppers and visitors at all hours. And these vibrant CBDs can attract the companies looking to recruit the next generation of employees, most of whom these days prefer urban lifestyles. But this shift in attitudes has left many suburbs in a quandary. How can these municipalities compete for the corporate headquarters, new residents, and retail outlets that provide a solid tax base?