I ask because someone on another thread made a statement to the effect of, "We all have an in-built need for excitement."

Well, I certainly don't, and I know a fair number of others who don't either. (We're kind of invisible to the excitement seekers, of course.)
I remember being excited as a kid, at a party for instance, and finding it so unpleasant I'd walk off to be on my own quietly for a while - it felt too close to dread or panic to be pleasant. As an adult, I tramp down hard on any feeling of rising excitement (during an impending eclipse, or on first seeing a major predator in the wild, for instance) because it has a cognitive effect similar to panic, and I want a calm mind to obtain full enjoyment from the experience. And I don't do fairground rides, because the only thing I ever get out of the experience is to reflect halfway through the ride, "I wish these people would stop screaming and shouting" and "Gad, this would be an embarrassing way to die."

There's a psychometric scale called the Sensation Seeking Scale, on which I have skewed results: Low on "thrill and adventure seeking", high on "experience seeking", low on "disinhibition" and low on "boredom susceptibility". Despite the fact I thought some of the questions were a bit fatuous in their underlying assumptions (mountain climbing and flying a plane as "high stimulus", for instance), that seems about right.

Grant Hutchison