The MBTA web site, which was formerly pretty awful and changed formats at the drop of a hat, at some point during the past year or two was completely overhauled. Now it has some of the things I always wanted it to have before, like a full system map
, and the trip planner is improved.
Getting from the airport to the meetup spot is not that complicated via the MBTA. There are only rarely confusing "express" trains, the subway lines are sorted handily by color, and you won't have to deal with split lines (the green line divides in four to the east, and the red line in two to the south, but none of that affects transportation between airport, downtown, and meetup locations). You might have to ask someone (oh no!) who works at the airport for directions to the silver line stop outside the terminal (they will be simple, e.g. pointing and saying "it's right there").