Here's a map I created showing a 10 mile radius around the actual Metro Center. The red dot in the center shows the point around which the circle is drawn. The five points near the edge of the circle represent the five largest jobs centers in the Metropolitan area.
Total number of jobs in each city:
Detroit - 318,790 (with a little over half in the Downtown area)
Troy - 105,445
Southfield - 94,386
Warren - 90,939
Dearborn - 87,946
Livonia with 83,368 is the next largest suburban job center, followed by Sterling Heights with 59,434, Farmington Hills with 56,072, Pontiac with 49,451, and Auburn Hills with 48,672.