The study rates 24-hour city San Francisco tops, followed closely by New York and Boston, with Los Angeles and Washington, DC on their heels. Atlanta, which ranks 12th, is one of the 9-to-5 cities in the same category with Phoenix, Philadelphia, Dallas and Detroit.

Investors do well in Atlanta, the study notes, but view the market as more risky than a 24-hour city, where demand often outstrips supply. Twenty-four-hour cities with an exciting center city combination of residential, business, capital, entertainment and shopping head the list.

Add to that mix, interesting topographic features and neighborhoods with character, the infrastructure for technology, mass transportation, lowered crime rates and an immigration population for the labor pool. Investors also like cities where supply is limited by geographic features, thus forcing a concentration in an urban core.