After finishing my streetcar plan, I decided to create a commuter rail plan:
The blue line is the existing commuter rail, and the red line is an already planned commuter rail. The green and yellow lines are my ideas.
The black dashed line would probably be a monorail to the stadium, ballpark, and Six Flags. However, I'm worried about it's capacity to handle big games (this is the reason the yellow line doesn't go north to the speedway). Both the stadium and ballpark have a lower capacity than the speedway, though.
The white dots are park and ride stations, and the yellow dots are not. All rail lines would converge at both downtown stations (T&P and ITC).