When my older son was working in New York City he was asked by a coworker for advice on touring these schools with her daughter. He gave some pointers. When the parent returned she was not happy. Her daughter was turned off by the Green Line tracks running through the Northeastern and BU campuses. The daughter was also turned off by the hilliness of the BC and Tufts campuses. So if your student does not like street car tracks and hills, be advised.
Seriously, I would recommend staying at a hotel in the Back Bay area of Boston. It is expensive but it would give you all a feeling for the urbanness of the city, as opposed to driving in from a suburban hotel. In fact, one of the two towers of the Sheraton Boston Hotel is now a permanent residence hall for Northeastern.
If your daughter is into STEM you should tour Northeastern’s new ISEC and EXP complex. Not sure if they are on the standard tour. If into computer science you must tour the new CDS building at BU, also referred to as the Stack of Books building. You can’t miss it.
Once settled into your hotel you should use the T to get around, as that is what most students do. Driving in Boston is a challenge, especially for the uninitiated. All four colleges are directly accessible from the various branches of the Green Line. Tufts is the latest member of the “streetcar college” club, although that new line has had issues since opening.
As mentioned earlier, BU has a concrete campus but with more open space than NYU. Northeastern is in a way like McGill in that it is very urban but nonetheless has a mostly defined campus with a surprising amount of greenery.
Tufts and BC are suburban campuses with a lot of greenery and open space. But they are suburban only in the sense that Medford/Somerville and Newton are not part of the city of Boston, The surrounding communities are older urban areas, especially Medford/Somerville.
As for student hangouts I am not current. Newbury Street is still popular, and I love Faneuil Hall Marketplace but that it not as popular as it once was. The North End is very popular for Italian food and pastries.