I interviewed at both places last year and did a visiting rotation at JHU. JHU is JHU, short coats, etc. Let's just describe JHU as not touchy feely; the interns appeared happy though. Bayview is a much more touchy feely community-esque program. There is a very wide range of abilities in the house staff at Bayview. The fellows I worked with described it this way. At Bayview they assume all of the house staff are idiots until they prove themselves, it's the opposite at JHU. And you would have to prove yourself again every time you had a new fellow or attending. If you are interested in Baltimore don't forget to check out the University of Maryland.
