Oh, hell...you've got to see a Vegas show. Nothing sleazier or more tawdry than that. Makes the French can-can dancers look like high art by comparison. A trip on the Mississippi can be cool or a total waste of time. Depends on where and how long it goes. In all probability, it is a short jaunt on a largish body of brown water surrounded by trees and industrial facilities. I'd definitely do the helicopter trip over the Grand Canyon, though...they hardly ever crash anymore.
Seriously, it is probably the best way to actually see it, short of hiking into it.