NASA Space Center Houston, Houston
When visiting Houston, you absolutely must go to NASA.
Fondest memory: My fondest memory of Houston is being eight years old and walking into the Astrodome for the first time with my parents and four older brothers to watch the Astros play the Expos.
Favorite thing: Famous NASA center which serves as both an astronaut training center and also the main communications center for NASA. There is an offsite museum along with tours of the facility.
NASA... the one and only.
Fondest memory: The only other places with better weather were Hawaii, Kwajalein, and San Diego.