The fact that it was written as a vehicle for John Belushi should give an indication of the type of humor they were going for. I believe I've posted my picks for a new crop of Ghostbusters but in case no one saw those:
Eliza Dushku or Alyssa Milano (or both)
Shia LeBeouf (Oscar Venkman)
Christy Carlson Romano (character similar to Egon Spengler or Kylie Griffin)
Seth Rogen (character similar to Ray Stanz)
Nick Cannon (character similar to Winston Zeddmore-can be a younger nephew of Winston!)
Great choices, or what?