I was just about to mark up an interview with the dialog tag, only to find it's been dropped from the spec. Now, plain old P tags are the way to mark up conversations/interviews/etc., which seems a bit loose to me.

In HTML5, <i> and <b> are for when 'typical typographical presentation' demands bold or italicised text with no semantic meaning, which matches how I use <i> (for phrases in other languages, book & film titles, &c.). Also of note: screenreaders ignore <strong> and <em>.