I've only been to a couple of weddings, and all when I was younger. What I do remember is there were not ushers at any of the weddings. The Groomsmen or Bridesmaids were the ushers.
Is this appropriate? I'm just running out of friends and family who are physically up to the job (like standing for more than 10 minutes). Do you even HAVE to have ushers?
I keep hearing about the seating of the parents and grandparents, but, again, this never happened at any of the weddings I went to. Everyone just sat down where they wanted, and when things were ready to start, someone usually shouted "Okay! We're Going to Start!" This sounds rather informal and tacky in my opinion, but I just don't know about ushers.