K.E.
My vote is NEVER open gifts, at any age, at the party. Kids can be MEAN. My son is 12 now and will never forget being 5 and having a snotty little brat open a gift from him at a party and shout out " I already have this with major disgust in his voice !" and toss it aside. He was just devastated. The mom just shrugged her shoulders. I wanted to slap her as well as the kid. It is NOT an opportunity to practice manners. I'm continually amazed at the lack of manners that abound at kid parties so if you think it is an opportunity, think again.
Parties for kids, even as old as ten can be complete chaos , the gifts don't get recorded, cards are separated from gifts and you end up wondering who gave what. It is also horrible if you have a child who has parents who are "well off "and gives an overly fancy gift and one whose parents are struggling to make ends meet and can't afford much.
The gift opening scenario is just rife with potential for disaster in my opinion.
The party is enough for any child. Then they have something to look forward to in a quite environment after the festivities are over.