Excellent Photo-ops, Free Parking and Admission!
If you are looking for something the kids will love, you can get some great vacation photos, and it won't dent your pocketbook...then this is it!
It is not a 'long' trail to the rocks. But it is uphill, at not a 'gentle slope' grade. So be mindful of that, especially if the heat is really ramping up! (carry a bottle or 2 of water with you if it is hot!)
If you are using GPS to get there, put 'The Hole in the Rocks PARKING LOT'...it will make a big difference in your walk!
There appeared to be other things to do in the immediate vicinity as well. (Papago Park: fishing pond, playground....) And restrooms. So you could pack a picnic, make a day of it and the kids would love it. (remember to either find shade or bring your own, and bring lots of water...VERY important!)