The ACA maps provide a ton of information for cyclists that takes time to find on your own: campgrounds, hotels/motels, convenience stores in the middle of no-where, great routes, etc. I know they seem expensive, but they provide a lot of info that cycle-tourists need/want when they tour. ACA is a non-profit that works hard to prodcue high quality maps (special paper for example that doesn't disintgrate in the rain or humidity).

That said, the ACA maps do not provide information off the route, just like adventurepdx said. What I do to compensate for this is to buy state Gazateers produced my De Lorme (more money, however) that have the right resolution for back roads in case you want to deviate from the ACA course.

My experience is that the routes are not overcrowded. The Pacific Coast route has lots of cyclists, but they had lots of cyclists before the ACA map of the Coast. On the the other routes, like the Trans-Am or Northern Tier, for example, if you saw two-four cyclists every day that would be a lot. One advantage however of the ACA routes is that the businesses/restaurants/hotels/campgrounds/gas stations are used to seeing bicyclists.