Admittedly, 117 degrees F may not sound like fun--but it's the desert. It cools off in the evening, and the mornings are almost cool.
We stayed in Twentynine Palms, but could have camped in the park, frankly. We enjoyed the park in the evening for hiking and photographing. We swam in the chilled motel pool in the afternoon--almost too cold. I drug two sleepy preschoolers out to bed well before dawn to hit the park before the sun came up, and photograph. It was wonderful to watch the sun rise, and to have the park to ourselves.
By late morning we hit the cool of the the visitor's center to watch a short film, turn in junior ranger packets, and overload on mementos (including stuffed snakes--which became so many things on the long drive home, including a linked rope that festooned the car interior). It was hard to peel the kids away from a family of quail, scurrying through the bushes.
At mid-day, as we reluctantly prepared to leave the beautiful park, I watched several families pile out of steaming SUVs, ready to enter. They grimaced in the sun, argued, and shlepped about looking miserable. We headed for super-size slushies, probably paid less than a dollar for each of them, and enjoyed the icy convenience store staple. There must have been twelve machines to choose from.