I had spent a couple of months in NYC and was totally inspired to recreate something for Detroit. I know it's not the best design for a map (I have poor graphic design skills), but I was mostly just trying to convey what I thought would be ideal routes for a subway system.
Emphasis is placed on clustering stations around institutions, job centers, and areas that would have the most potential for high density development. All or most lines would have an express train and local train. Low density areas wouldn't have much coverage, but most would be covered by feeder bus lines anyway.
One main thing is I wanted to avoid is using the spoke roads too much. That's why, for example, the "Woodward" line (W1) makes a turn at McNichols and then turns north up Livernois. The Grand River line (G) makes a turn up Dexter and then a left onto Fenkell and rejoins Grand River at Southfield Freeway. Michigan (M) would actually follow Vernor Highway through its section of Detroit then reconnects to Michigan Avenue via Miller Road. This way, many more sections of routes go through the heart of residential areas than if they were stuck to the spoke roads.