I really appreciate the excellent viewpoints from everyone.
I think I'm leaning toward Sunday. Two main reasons being:
1. The tackiness of GOH leaving early. I know some said this wouldn't bother them, but I tend to feel it is on the rude side. Plus with the distraction/excitement DD#2 will probably have about the concert, she won't be able to give full attention to all of her guests.*
2. The "friend" issue, which I didn't even think about at all. True most friends are as close as family and they've been to plenty of family parties so they know the relatives, but this way she could invite other not-so-familyish friends.
I also think this would probably work out better for the Gparents. They won't feel rushed to get here.
And thanks to those that said I was projecting . . . you're right, I probably was without realizing it because I really would prefer a Saturday party.
*As far as the party being "rushed" on Sunday, thanks to your responses, I now see that DD#2 would feel more rushed with her guests if the party was on Saturday.
I'm so glad I posted. Once again you all have helped me see the individual trees within the forest.