I went for a fairly narrow band myself because I don't like to wear rings very much. It's pretty rounded and fits nicely in the bend of my finger. It's funny. I got my wife's ring in China. I thought I was buying white gold, but I bought platinum. I asked if it was white gold, and they said it was. Apparently platinum is called 'white gold' there. It wasn't until a while later when she had the setting fixed that we found out it was platinum. I'm clueless about that stuff, I guess.
I say keep it timeless so that your great granddaughter will want to wear it. But who knows, maybe your great granddaughter will take it, melt it down and make it in to a band with the Black Lantern symbol on it? My brother recently got married and his officiant ended with, "and now by the power of Grey Skull, I now pronounce you man and wife". -It was awesome. Congrats by the way.