It’s such a shame to waste such beautiful flowers and elaborate arrangements by leaving them behind/disposing of them after the reception. Some alternatives:
Transport them for Sunday brunch
Gift them to those who have helped you prepare for your day
Donate them to hospice, hospital or nursing home (your florist, coordinator or friend may be willing to do so)
As for the bride’s bouquet, send them home with someone who is willing to hang them in a dark, dry closet. You may want to designate someone before your wedding day.