ram wrote:It's just about getting in a good position - e.g. if you end up lower than the subject - bride and groom up on a stairway or some other reason - getting yourself higher helps. They are looking down less - reduces unflattering lines on the neck (brides not that keen on double chin effect). Also, raising yourself up means less angling of the camera so less distortion (converging verticals) if you are shooting wide which you often will do if you are trying to get a lot of staircase in.
Step ladders are used for group shots, so people towards the back of larger groups can be seen in the photo.
Group shots are like hearding cats. Make sure you have a list of shots, an usher or someone who knows who is who to help you and try and get them before they have had a drink - it'll be much quicker. And shoot with small apertures - you'll want everyone in focus!