Hi Steph,
I did this trip about 3 years ago and it was fantastic, as Jim says they have turned it around so you start in Vegas and end in Rapid City, as far as I am concerned that is a bad idea, but I am not the one who arranges the holidays.
If you have never been to America then you must fly the Grand Canyon, I didn't when I went as I had done it back in the 80's
This trip now only appears to have 2 optional trips, quite a lot of what is now included was optional when I did it, the Great Salt Lake was interesting, so why not do it.
If you are interested in Geniology (have I spelt it right!!!!!), then when you get to Salt Lake City go and spend some time with the Mormons who will search things for you, I spent about 3 hours with them and it didn't cost a penny, but I left a donation when I had finished.
Again as Jim says, the views are incredible and the colours fantastic and I can go one better than Jim, when we were in Yellowstone we saw a Bald Eagle, vary rare apparently.
Have agreat time, if I can be of any more help, get in touch.
regards,
Martin