To demonstrate the diversity of choices and the need to investigate each school individually, here are some examples from your list. You can visit, e-mail or call and the departments will talk with you about whether or not the presence of BM students means fewer opportunities with teachers or performance for the BA students. Go to concerts if you can.
Northwestern’s Bienen School of Music has a Bachelor of Arts in Music option (with the same distribution requirements as arts and sciences majors)
http://www.music.northwestern.edu/academics/degrees-and-certificates/bachelor-of-arts.html
http://www.music.northwestern.edu/academics/areas-of-study/composition-and-music-technology.html
I noted there are no private lessons in composition for non-majors.
Indiana Jacobs has a BS in composition and another field:
http://music.indiana.edu/degrees/undergraduate/requirements/BSOFComp.2014.pdf
This seems like a very serious composition path and might be arduous with science but high quality.
For St. Olaf’s, scroll down to composition here: http://catalog.stolaf.edu/academic-programs/music/#header They require composition applicants to audition on an instrument of for voice, and you have to study that too.
College of Wooster http://www.wooster.edu/academics/areas/music/major-minor/, Oberlin, Lawrence, Bard and Ithaca all have both BM’s and BA’s. Any of these schools will talk with you about the differences in opportunities for composers in the two degree programs.
An LAC like Grinnell http://catalog.grinnell.edu/preview_program.php?catoid=14&poid=1541&returnto=3144 considers music “one of the 7 liberal arts” and has a general music program with the opportunity to focus on composition, with a curriculum that is offered to every student in the college. However, you would have to find out if there are composition lessons, because it looks like “applied music” faculty do not include composers so probably not!
There are many many LAC’s with general music BA programs that include composition but you would want to find out whether a teacher is available and what performance opportunities there might be. But you would also want to look into the sciences or whatever else you might be interested in. You can enter med school with a BM- I assume you know that- if you do the prerequ’s between college and med school or manage to do some during undergrad years. There are post grad programs for the prerequ’s.