The aim of our trip was to cover the distance quickly. We did LA to NY in 29 days stopping in motels and having no rest days. The time factor meant camping, or carrying extra equipment, was out of the question, so it was motels all the way in a fairly straight line planned using Google maps. I would agree with whoever said that sticking to ACA routes will mean you meet more cyclists. But it depends on whether this is important to you.
Crime: We felt safer than if cycling through Leicester after dark. Maybe some of this is a false sense of security, maybe it was our route through small-town America, I don't know. But there was a complete absence of that irritating anti-social behaviour that blights the UK (youths hanging around on the streets looking to abuse passers-by, children drunk in parks etc). The exception was North Las Vegas, and after dark in Newark New Jersey. The latter made Peckham resemble a sleepy village. My perception (and I may be wrong) is that crime in the US is much more concentrated in particular areas of towns, whereas in the UK you can just as easily get mugged in the good and bad parts of town. My advice would be route around major urban centres unless you have detailed local knowledge. We did that around Indianapolis and Columbus and it seemed to work well
Kit: Be completely comfortable with your equipment. Get all your kit together three months before you go and be sure you can carry it comfortably and ride some distance with it. Don't think you have to train 100 miles a day in preparation. Your fitness and conditioning will come. But don't make the mistake my brother-in-law did of buying a brand new bike and setting off from LA having only done about 10 miles on it previously. Take your own bike rather than buy one there. We flew Virgin and it is free to take it with you, and they are really flexible.
Route: We had the wind behind us for about 27 of the 29 days although to be fair it was never more than 5-10mph in any direction. Maybe we were lucky. However, the couple of days we rode into 10mph winds were noticeably more difficult and far less enjoyable, so I would defend West to East every time.
I've typed enough. Will add some more latrer.