Having driven here from Las Vegas in August, reading the other reviews, I think your experience will depend a lot on the weather and the time of day you go.
We got there after 4pm on a Wednesday and it was a lot quieter then (I'd recommend getting there before 3pm though so you're not quite a rushed as we were). There was no queue for tickets and we waited just a few minutes for the first bus (and none for the second).
It was a very memorable experience and all the staff were friendly and helpful. We eat in the restaurant and the view while eating was breathtaking.
So why 3 stars?
Firstly, Hualapi Point was skipped by the bus completely because it was already closed. This was never made clear to us until the end and no discount was given.
Secondly, it's costly. It's understandable in a way but £200 for two adults and a kid is a lot, especially when you add on food and photos, which brings me to...
Third, the restrictions on the Skybridge. We didn't have to wait at all to get on to it but it's nuts that you can't take your own photos. No matter what they say, this isn't because of risks of phones bring dropped as the next stop doesn't even have railings and you can fall off easily. I don't mind the option of having photos taken but it's just nuts that you can't take your own.