I got married in the Grand Canyon too!
We took two helicopters to carry us, family, the photographer and the minister, and the company provided everything - flowers, cake, photography, etc.
We had the ceremony on a bluff by the river that is no longer allowed to be used, I think we were one of the last weddings there. We definitely didn't have to repeat our vows on the way back though, I don't know if that's a new thing.
We were fairly chilled about it and didn't want a huge fancy cake (it was small but so delicious!) or care in any way about the flowers.
We were a bit disappointed with the photographs though, they looked like a family member or friend had taken them rather than the beautiful professional photographs that a lot of people have. There are a few nice ones, but nothing really wow.
We booked a private room above a restaurant in the Venetian for dinner with family and friends afterwards, we literally walked in the day before and asked what they had. I shudder at my lack of organisation now I'm looking back at it!
If I could do it again, the only thing I'd change is that I'd take my own photographer with me. Other than that, it was amazing!