Acme Mapper
 

I've recently been turned on to this mapping program. I like it, but haven't really explored it's usefulness for touring yet. The topo maps are nice as well as the nexrad radar overlay.

http://mapper.acme.com/

As far as I understand you can view ArcGIS produced maps and layers with it, but I haven't discovered how yet.

ACME mapper is the greatest thing ever for backpacking, Ive used it for quite some time, but I'm not sure how well it would work for touring. The advantages of ACME is that it includes trails and trailhead names, which makes it awesome for backpacking, but I think just a regular map program like google maps might work better for touring, where roads are the main concern.