I also have a draft of a third route that connect the Magoun T stop with the actual Magoun Square simply because it annoys me that those two are so far apart. Even extending that though, there weren't really a lot of big population centers (just Maxwell's green and the Lowell St VNA) and things to connect them to... maybe Porter for Shopping and T? Then you have another Red/Green connection as well.

4/probably end

this second route connects folks to grocery stores (the stop & shop and potentially the whole foods) and the Dilboy recreational facilities. It serves dense housing with the VNA on Alewife Brook and Clarendon Hill. While the Davis - Clarendon Hill segment is covered by a few MBTA bus routes, it seemed ideal to connect these to the Red Line.

I also half debated extending the Northern end to the Green Line at Medford/Tufts, though that runs primarily through Medford.

3/

Davis to West Somerville: I have a number of friends who live over in West Somerville, but it is very difficult to get to them via transit. This route would go from Davis through Teele Square, stop in the Clarendon Hill bus loop (couldn't make the mapping tool show it) then head up Alewife Brook Parkway. I would have liked to take it up to Boston Ave, but couldn't figure out where to turn it - maybe the Whole Foods?

2/

Assembly to Market Basket: This is my favorite, as it connects some areas of the city that are rather hard to get between: Assembly Row and the Orange line there, to Ten Hills which currently has no transit access, to the mystic apartments, to winter hill and the future 299 broadway site, to City Hall & SHS, to Market Basket, then to the Wine & Cheese Corner before looping back up. These are all places that
1. A lot of people live OR travel to, and
2. Have terrible transit connectivity now

2/