Houston's scale is its most disorienting quality — the city covers over 600 square miles and most of it looks the same from a highway. What makes it work for visitors is that the best experiences are concentrated in a handful of distinct neighbourhoods and destinations. Plan around them rather than trying to cover the city comprehensively.
The Museum District alone is worth several days, with the Museum of Fine Arts, the Menil Collection, the Rothko Chapel, and the Houston Museum of Natural Science all within walking distance. Space Center Houston, NASA's official visitor complex in the Clear Lake area 40 km southeast, is unlike anything else in the country. The Hermann Park adjacent to the Museum District has a Japanese garden, a free outdoor theatre, and the Houston Zoo.
Montrose is Houston's most interesting neighbourhood for wandering — a grid of bungalows, galleries, and independent restaurants with no equivalent in Texas. Downtown has the Theater District, Market Square Park, and Sam Houston Park.