Per the previous post, here are a few images of layered fractals. Unfortunately, they're not as impressive as I'd hoped as it seems like when one fractal is bright, the other is dim. Rarely if ever are they both bright at the same time. The other problem is that they aren't as organic as I wanted them to be, since using different formulas for each results in images that don't line up nicely and using the same formula for each results in images that look too similar, enough that you often can't tell where one is vs. the other. Nevertheless, they're still pretty cool.
I also made a few more improvements to the fractal generation itself, most notably introducing multi-threading logic to the (embarrassingly parallel) pattern generation so that generating ten two-fractal images went from taking about 50 seconds on average to taking just 20 seconds on average. I'll take a 60% speed improvement anytime.
(Edit: I forgot to apply my previous optimization for those numbers. With both of my optimizations, the multi-threaded version takes 10 seconds to generate 10 two-fractal images while the one-thread version takes 30 seconds. With none of my optimizations, that same set took about 50 seconds to generate, a total improvement of about 80%).
And here's a couple single-fractal images I just thought were really awesome.