These type of character roles are extremely flexible, as business casual will cover most of them just fine. If you want to put your own spin on your character to get a laugh or two - feel free to do so - it's a party! Therefore, if you are an author - dress up as Jane Austen or Edgar Allan Poe or a reporter, be Veronica Cornerstone or Ron Burgundy.  Or, you can simply make it your own.  If you're part of a news crew, you can essentially wear anything, but if you wanted to dress up a bit - choose a business suit.  For news media/tabloid roles, pick a fedora and put a card in the brim that says PRESS or get a lanyard and make your own press pass.