Amazon recently announced plans to spend $1.4 billion to expand its workplace hubs in New York City, Dallas, Detroit, Denver, suburban Phoenix and San Diego, creating 3,500 new tech and corporate jobs across those half-dozen sites. The locations had at least one thing in common: They all are part of the top 20 markets for tech talent, as ranked by CBRE in a special July report. The real estate services firm scored the regions based on 13 metrics measuring "each market's depth, vitality and attractiveness to companies seeking tech talent and to tech workers seeking employment."