That looks awesome, the first one would remind me of some sort of El Dorado with an alien oblivion portal opening above it (don't ask me why I thought about that).
How much time to render each one?
Well, the 3D stuff are what take the longest to render and what takes the longest to make. Probably 70% of the process consists of arguing with the navigator, and it is CONSTANTLY trying to re-render the preview image during the entire thing.
Here, have a look at this:
If you've never used Mandelbulb 3D before, that's an example of some of the process of making one of those. You can see the whole thing blur in and out as I move sliders and shift the camera. As you might expect, the complexity of the object changes that quite a bit. The object in that pic up above is much more processor-intensive than the one in the video, so everything took far longer. I'd say the final render probably took about 2 minutes to do. The purple background was done in JWildfire and took almost no time at all, it was very simple.
That green & violet spiral thing with the bit in the center, probably about 30 seconds. Technically that one was rendering 2 at once, the "star" in the middle is actually copy of the very same weird spiral thing, but with various values changed and a different gradient.
Also if you want to see a bit more, I did this blog post not too long ago:
Learning some new stuff. Complicated stuff.
Also shows the finished version of what was in the video. The final renders are always the longest.