I've used two of the ACA routes and thought they were definitely worth the cost. I even recouped half my cost, the last time I bought their paper maps, by selling the annotated set. Often the route will include some tips on free lodging or camping for cyclists only. And if you're traveling solo, there's the benefit of perhaps meeting up with a companion.
On the other hand, I also enjoy making my own routes and exploring a bit, which is what I usually do.
I avoid limited-access roadways like interstates whenever possible, simply because they just suck the soul out of me. The comment about traveling while seeing nothing is spot on.