Im planning on riding across country this summer, mostly off ACA routes, and hope to use a combination of printed (state) maps and my Android phone. I think phone GPS would be too costly (in terms of data usage and battery life), but it might be there in a pinch. I want to download maps ahead of time using wifi, though I haven't picked a program yet.
I just cant justify the increased cost and weight of a dedicated GPS, though Im sure that'd be the best.