When I was in Dallas last, I tried to go to the Perot Museum of Nature and Science. However, the tickets were completely sold out for the day. The building itself is an awesome piece of architecture and I snapped a few pictures.
The Newport Aquarium is slightly over priced but it was so cool. I will have a more robust post when I upload the pictures from my camera but here is a peek. Also, there is a penguin encounter that I really want to go back and do!