If there is one thing I learned in Vegas on this past trip is that it can be "kid friendly" but keeping kids entertained still comes at a hefty price. So considering that all of the activities are expensive, I considered ourselves winners if we actually enjoyed ourselves, despite the price tag.
Shark Reef Aquarium at the Mandalay Bay was expensive ($18/adult, $12/child), especially for the size of the place and what was essentially a 45 minute visit. However, our entire family enjoyed ourselves immensely for the time we were there.
The place is much more modern and up to date looking than Dolphin Harbor at the Mirage (which looks like it needs a good sprucing up). The marine life was phenomenal and presented in a stunning environment.
First there is a little maze with small tanks holding various species of marine life, as well as some snakes and a Komodo Dragon. There is a large room with a stingray pool, a large jelly fish tank and a big lion fish tank which are all fascinating to lim at. The glass shark tunnel was incredible; Walking through a dry space with sharks all around is quite an experience. The last room has a huge tank with more sharks and plenty of exotic and not so exotic marine life including a sawfish. Believe me, I am the only non fisherman in my family and even I was impressed!