Just MHO: ACA routes are a great way to start bicycle touring, and a good way to find decent route with minimal hassle.
ACA routes range from inspiring and breathtaking (roughly 20% of miles) through pretty good (70%) down to passable (10%). It's possible to find other routings, especially with the advent of crowd-sourced sites like ridewithgps or Strava. In the west, there's often only one road you can take for 30-60 miles, so once you've picked a couple of towns, routing between them is easy. Routing through Kentucky, OTOH, is more like the old Adventure computer game: you're in a maze of twisty little passages, all different.
If you're going on your first long tour, you've got enough other things to keep you busy, like picking a bike, perhaps, and choosing how you're going to carry your gear, what you'll take for sleeping (or making reservations), how you'll cook, what rain gear and cool weather clothing you'll take, etc. The ACA maps will give you a good route, along with information on where you can get food, water, lodging (either for light loads and every night motels or B&B, or for emergency shelter) or camping locations. The maps make that part of planning easy.
As noted above, some roads have shoulders, some don't. Crossing Kansas turned into a game several days: are we going to cover more miles (say, 20 miles) or see more cars (maybe half a dozen) before lunch? Once you get out of the cities, it's amazing how much "nothing" there is in America! Make sure you've visible with brightly colored jerseys or jackets, focus a bit on holding your line when there is traffic, and odds are you'll be fine.