We stayed in the Bellagio - and they have partnership with a company called Maverick. Bellagio said they go with Maverick as they have a new fleet and their safety record etc is excellent - etc etc etc!... All very nice to hear!
However Bellagio charges an arm, a leg and a few toes, throw in an ear - and some fingers for the honour of going via the hotel.
Before we paid the expensive price, we went up to the information tourist centre we found just down the road. They also offer Maverick Packages - exact same brochure / deal - however the price was a whole lot less - almost 200 less each!!!
On the way back, the pilot - who was fantastic - decided he'd go and do the Las Vegas Strip for us on the way back - this was NOT part of our package!...
What was great about this Maverick Deal was that - when you stop at the canyon - the pilot swaps passengers around on way back (only 5 on our trip) so everyone gets to sit up front or by the window (even though all views are fantastic no matter where your sitting)!
I will try and find the information centre details for you.. but my advice would be NOT to go with your hotel... and to shop around first!