Cascade Falls is a pretty diminutive 20ft waterfall, but it was one of the "easier" waterfall hikes we did in Marin County, and it seemed there were a lot of memorable things about the excursion itself.
For starters, the waterfall sat within the Elliott Nature Reserve, which itself was at the end of a road within a residential area. We didn't expect to find something this naturesque with civilization closeby, and even then we were pleasantly surprised by the absence of urban blight that usually accompanied places close to development. In fact, we were even surprised by a wild turkey that dashed out in front of us during our hike.
I've read that there's also an upper waterfall beyond the main falls, but we didn't do it. From what we could tell, the trail didn't go beyond the waterfall.
The 2-mile round trip hike along the High Water Trail undulated on some minor hills with some minor dropoff exposure and some minor rock hopping on tributary streams. After crossing a bridge over Cascade Creek, we turned right and follow the trail alongside the stream until we reached the falls itself. We believed that this was the shortest way to go though there seemed to be plenty of other ways to do this hike.
To get to the trailhead from the town of Fairfax, drive on the Fairfax-Bolinas Road for about 0.3 miles (passing through a pretty charming part of town) until it intersects with Cascade Drive (there are a pair of pillars flanking this road).
Follow Cascade Drive (passing through a residential area) to its end at around 1.5 miles. The Elliott Nature Reserve begins at the end of the road, however, you'll have to find parking as signs there prevent parking on the pavement and some prevent parking on one side of the street. Furthermore, you'll want to be mindful not to block anyone's driveway.
The effect of all these restrictions is that you'll probably have to find a pullout further down the road, which will increase your hiking distance a bit.