We stayed one night in Cabin #17. Because we visited off-season, we were one of only three cars parked in the cabin/camping area. The beds were comfortable and the air-conditioner kept the cabin cool while we slept. There were a LOT of bugs that got inside the cabin, which was somewhat unavoidable every time we openned the door. 

The night we stayed was a new moon, so the dark sky views were INCREDIBLE. We saw the milky way with our bare eyes sitting on the porch of our cabin.

We arrived around 10pm at night, so the check-in desk was already closed. Fortunately, I had received the email with the late check-in instructions, and finding our cabin assignment was easy. I do wish getting some information in advance had been easier. I tried to call the front desk on our drive to the park, but no one answered. It wasn't entirely clear what amenities/facilties were open. For example, the website said breakfast available in one place, but in another place it said the only open was getting a breakfast burritio in their gas station. So we didn't know if we should pack extra food.

It did turn out that the restaraunt was still open, despite being off-season. It was pricey (totally fair, you're in the middle of a desert) but delicious, and friendly service. The staffer in the general store/gas station was also really friendly and gave great advice for which parts of the park to visit, and how to drive responsibily in the summer heat.

Finally, I think it goes without saying, but coming in July will be HOT. Plan to do activities like hiking early in the morning, and find some place by noon to stay in the air conditioning until evening.