Marco's apartment was perfect for our 8 person group. The front bedroom has two double beds and a twin. Second bedroom is a king. Third bedroom is two queens/doubles. Last bedroom is one double/queen. There are two bathrooms and a moderately sized kitchen. The backyard is paved and accessible.
The apartment is clean and well lit. The beds are comfortable. There are two locking doors to enter.
The location in Dorchester is fine. I know some neighborhoods are iffy but this seemed to be all family homes. You don't have a lot of stores or restaurants around but there is a good pizza place up the block on Columbia. We went into downtown Boston via uber/lyft and via the bus (17) and Red Line at Andrews. It was fairly efficient even though it was the weekend of the Boston Marathon and there were big games (Celtics/Red Sox).
Parking is fairly limited. We were able to get a spot on the street every night but our group only had one car. I think if you have more, it would be tough. You must be able to parallel park.