Inkscape can import a vector PDF one (or .ps, IIRC) and is a good place to do the editing or compositing. Such as (low quality JPEG):
If you edit and don't use fancy gradient fills, transparency or effects (ala the above), then you can export to PDF as a vector format - which would be best for PDF and print and could easily match the CT color world maps, IIRC. Otherwise a big size is usually in order (150 ~300 DPI minimum depending on how 'smooth' the color transitions are).
Cosmographer/CC approach isn't free, but does have some specific tools geared just for this. There was a thread on this forum that could be of value. However, a learning curve is still probably gonna exist for you regardless of package (and Inkscape is not only free, but more general purpose and runs on numerous platforms).
If expertise and $$$ was not an issue - you could make it in illustrator or even just a text editor (i.e. raw PostScript 3), which support tensor gradients ala:
Or see this for something more 'natural' looking...
Yep, those are full vector images
But, that is all a bit over the top, if you are trying to accomplish a goal (ala hardcopy of a creation), suggest trying to setup the layout so the pages can be replaced/done last. Otherwise, you may loose steam attempting to learn and do things that you've already basically done, just aren't happy with the quality of...