Photos lacking color saturation, what am I doing wrong?

Anything auto is shit. Just stick to manual.

Also, you're not showing any examples, so I can't tell you what exactly went wrong and how.

You're making this out to be far more complicated than it has to be.
I will have to see if I still have the images, I may have just deleted the whole batch because they were junk.
Eh... auto can work, but probably not to the standards of a professional. :p

I took this on auto+
though i tend to adjust colors a little bit in PS afterwards.
On my canyonlands trip I tried to take more control of the camera, using the aperture priority setting. So what did the camera do? Decide to max out the ISO so everything was overexposed all to hell.
Since you were in aperture mode and your images were overexposed even setting the ISO to minimum, did you happen to notice the Exposure Compensation. I'm not familiar with your camera, but, I suspect there is one. If set too high, it will blow out the images. Your ISO (or auto-ISO) may have been what it's supposed to, but, the Exposure Compensation add/subtracts from it. Ex: if set to +3, that's 3 stops over exposure.

Also, don't you chimp from time to time. If not, you should.

- - - Updated - - -

Just in case you didn't know about the Exposure Compensation, if this is your camera, down-right of the power button there's that +/- button. You want to start off at 0, then, adjust to taste.

Reading through this thread, i'm realizing how little i know about my camera.

Maybe i should take some lessons in photography or something, learn a little.
I've been meaning to write a bunch of tutorials about this and other things I learned at uni. Maybe a good time to resurrect my blog.