I've been to Vegas dozens of times and decided to make time for the aquarium for the first time, and I wish that I didn't.
It was dark, the reptiles were in small enclosures, and it was just sad. The jellyfish were cool, but that was about it. I wish that I would have spent my time and $20 for a drink by the pool rather than contribute to fish confinement.
No doubt that the engineering of the space is impressive, but so is the lazy river.