To be honest, I can't think of too many instances where the elderly or injured/disabled have issues at a wedding. So I don't have much here, but you can keep in mind that when making certain decisions like location, it can affect people with handicaps. Example: outdoor weddings can cause problems when there is extreme weather (like heat). You can either use your backup location, or maybe have a tent to provide some shade. Definitely make sure there are usable bathrooms nearby at all times for those who can't go very long with a bathroom visit. Try to keep the main path off uneven ground. Have enough space between tables for a wheelchair to maneuver. Things like this.