There really is a lot of good exploring between all of these areas. Personally, I like staging at Plaster City as it's closest to me (San Diego) and it is usually deserted for the most part unless a race weekend. It's 10 or so miles to Superstition, which can be done much faster on bike than driving the side roads to stage out there. From Plaster City to O. Wells is roughly 40 miles. As Rory said, gas is available in Ocotillo, Ocotillo Wells, and I think there is supposed to be a new station in Salton City, but would need to verify that. Food/supplies are available at all three. I always crack up that people talk about blow sand hill as some reason to go to Ocotillo Wells. The reality is that there is about 100 times more sand dune area at Superstition if you're into that kind of thing. Between Superstition and O. Wells, there are enough washes to explore out there to make you dizzy. But yes, the majority of the area is flat with a few exceptions.
I'm hoping to do a nice long loop in early December circumnavigating the whole thing if anyone is interested. Plaster City-Superstition-O. Wells-Truckhaven-Salton Sea and back About 120-130 miles or so if anyone is game. Will have some stops, but will keep to a decent pace to get it all in.
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