First I stumbled on Willow Creek Preserve by noticing some trails marked on Google Maps that were outside of the (also awesome) Pomo Canyon. I noticed cars parked in a trailhead-like way along Coleman Valley Road and I KNEW you guys were holding out on me, and sure enough I found it.
Then I had a little of the ol' patello-femoral recently from a minor acute injury going up stupid Collier Springs Trail in Marin County Watershed land, but still major enough that I don't want to exacerbate it. Was thinking of going up to Wright Peak at Clear Lake, but considering the trail is described as steep and loose, exactly the kind of terrain that caused the injury in the first place, I decided to check out Las Posadas State Forest. Well that's closed. BUT immediately adjacent, I stumbled across the quite-awesome Pacific Union College Forest, popular with bikers, through which the Bay Ridge Trail runs. Even on a holiday weekend-Friday it was still fairly light. It's amazing that I'd never even heard of this place a 45-minute drive from home and it's pretty sweet.
It's interesting to see how each valley over gets progressively drier (Santa Rosa plain, then Sonoma, then Napa, then Pope/Berryessa.) The redwoods and Douglas first more or less stop on the west side of Napa, the east side of Napa looks drier than the west, and once you've over that (into Pope and Berryessa Valley) it's mostly chaparral and a few ponderosa pines and much of it, especially the Blue Ridge on the east side (i.e., the last ridge before the Central Valley) the often eroded-looking dry sandy scrub could pass for SoCal.
After that I gave into my morbid side and found the island (above) where one of the Zodiac Killer's attacks happened. After the dry Mediterranean summer, peninsulas emerge connecting these islands to the shore, as was the case in September of 1969. To take away the fun of figuring it out on your own - it's on the west side of the lake, at the south end of the Oak Shores Day Use Area, near the Lake Berryessa Field Office; nearest mile marker 6.75 along Berryessa-Knoxville Road. It turns out the victims were PUC students as well (I'd never heard of PUC until I ran in their forest mere hours before.) Helpfully, the killer called the sheriff's office that night though boaters had already heard the victims' cries for help (they did not immediately perish) and to further clarify, the killer wrote in marker on the couple's car door "Vallejo 12-20-68, 7-4-69, Sept 27-69 - 6:30. by knife". I've visited the first two locations as well and barely remember what they look like - this one leaves much more of an impression.
In August of 2008 I jumped in my car and headed east from San Francisco, intending to correct some deficiencies in my experience of these United States - namely, some areas of the western prairies and especially the Black Hills. For many reasons the Black Hills were the surprise of the trip - with some pretty cool caves, and for being a transition area between prairies and western mountains (like

I mean come on.
Above, the trail up to the top of Scott's Bluff. Next two, vegetation in the area.
There is a Pony Express plaque on the old Wells-Fargo building in the Financial District of San Francisco. I and some other deviants have run the
Above: Carhenge, the Crown Jewel of Atlas Obscura. The wheels on the individual monoliths (autoliths?) still turn with minimal effort. Below: Kimball, Nebraska, the furthest east I have driven since moving to California.
This is from the Gordon Wells exit, #151. The other side is Grays Well #156. (This picture is facing ENE, and those mountains are somewhere in Arizona northeast of Yuma.) You can get to the dunes, which extend north, from 78 just east of Brawley too, about the same drive time from SD. When it's cooler there will be far more ATV's and dirt bikes, other than the preserve north of 78. I should add that when I called BLM in El Centro they were extremely helpful in planning this little excursion (and no I'm not being sarcastic for once.)
When most people (including me) think of the Sonoran desert they think of saguaros and areas that can actually get a little green from monsoon moisture - not this. But then I remembered that the northern end of Baja's Gulf Coast is very sandy like this, and loaded with saguaros, so even by that definition it still sticks. So whatever. (When I was there I thought this was part of the Mojave. Mojave, Colorado, Sonoran, I can't keep them straight.)
I only saw one person, a very kind dirt bike rider who was kind enough to ride basically from the horizon to see if this goofy black-wearing runner was okay. (Black? Safety first; always wear light clothing.)
In this area, the border with Mexico is only a few hundred yards south of the 8. Kind of looks like we already have a wall...