When looking for a better way to reach my old Head's Up Hyde Park cache (now archived), I looked up and to my delight noticed something I'd never noticed before -- a true arch in the gray rocks by the caves on the mountainside. This cache gives you a nice view of the arch and the city below, provided you come at the right time. I returned late one afternoon and had trouble spotting the arch, thus my name for the arch and the cache.
If you have a high-clearance vehicle, you can drive to within 300 feet or so of the cache. Otherwise, you can park about a quarter-mile from the cache (guesstimate.) There is a short, fairly well-defined trail up the ridge to the cache area. You could maybe get a mountain bike up it. (I sure wouldn't want to try it.)
This canyon is really popular with target shooters. They USED to stay in the area near the mouth of the canyon, but now that that area seems to be courting development, they have moved to sites that bracket this ridge. Just use caution and sense.