I prefer my own research to "pre-packaged" as with the ACA stuff because I don't know what they considered but left out or just didn't consider/know about. Planning a trip is almost as much fun as doing a trip.
I think for pre-trip "route planning", as opposed to being out on the road, large scale maps are definitely valuable - even atlas sized maps. With today's digital technology, I can "carry" a lot more maps and on/off-route information than ever before. Knowing I have information available before I leave for when/if I need it (like bailout points, plans, mail drop points, etc.) on-road means I don't have to worry about it while riding.
Once out on the road, weight and space come into play, which is where the pre-trip planning really should help out. I Xerox a regional map to cover my entire route on 1 8"x11" sheet of paper and annotated it with numbers showing the key off-route diversions/places that might be needed or of interest --- like nearest big city/town with a bike shop, car rental, bus station, etc. Numbers & dots with major city names on the map side, explanations of the numbers on the back side. Bailout points are something I feel should be researched at least minimally ahead of time, for example. I have another legend with interesting side trips/touristy sites on a 2nd sheet also covering the entire route. These are the only 2 maps that I feel I NEED to have plasticized and carry with me everywhere. Between these two sheets and the more detailed route sheets I've made, I don't think I carry more or less than is needed or useful but I don' thesitate to add a map while enroute if appropriate.
One thing I've been lucky with is I have been "into" map study of the continental US since at least elementary school (I remember a big ole National Geographics atlas I used to pour over in the early '60's). That and a love of American history really help researching a trip. Start with THE purpose - the most important thing/place to see and where I want to start/end - then pick an appropriate time/length for the trip, finally scrape the pennies together and begin to figure how much of the "dream trip" needs to be whittled away to be feasible within those constraints. During pre-trip planning, I add things/days for adventures along the main route for the purpose of breaking any sense of riding monotony or for the purpose of having reached at least some goal should the trip need to be cut short for some reason after actually getting out on the road.
Most of this "method" and perspective was developed as a backpacker/hiker and proved very useful when I did the Appalachian Trail and parts of the Pacific Crest Trail and also while car-touring the American Southwest. The transferables from those experiences include: emergencies are emergencies - they must be dealt with as they happen; there's never enough time to do or see "everything"; enroute surprises & discoveries are opportunities to change one's best laid plans; weather can be planned for but Mother Nature should never be underestimated. Finally, locals always know how to get to the next town; if they can get there, I can get there.