I think a 24-70 mm F2.8 and a 70-200mm lens would give you the most flexibililty for event photography. If you don't have either, you need a wide-angle prime lens like the 28 mm for group photos at the table, a short telephoto like the 85 mm for head-shoulders portrait or small group shots. Depending on the crowd the 85 mm will force you stand further and people may get in your way of your shot. Also, having prime lens only, will require you to switch lenses more frequently and you may miss an important shot if you do not plan properly.