I have some guides set up on my image that I wind up getting confused with other guides, and I have to pull back and examine the image to tell which guide I am trying to follow.
Is there a way I can distinguish one guide form another? Like make it change color? Or maybe assign guides to particular layers and then switch said guides on or off?

I don't think you can apply them to particulars layers, but you can double click a guide and can change its color.

Sweet! Thanks!

I either made a feature request for that, or I was thinking about it.... I think I posted the question on the mailing list, to find out if it was possible, before I made the feature request. If I recall correctly, it sounded like it was going to be hard to do. And since I've already made more than my fair share of feature requests, I don't think I actually ever made the formal request.

But yeah, I tend to use guides prolifically, and it would be awesome if Inkscape could have guides by the layer!