Driving is certainly 'easier' but you spend your days, well, driving. Not a real vacation unless you have a friend to share driving with. I think you'd meet a heck of a lot more people on trains and buses if you're traveling alone--you'll meet the upper class on the trains and the lower class on the buses, with plenty of exceptions. If what you want to see are the main cities, coasts, and a few national parks, trains could work. Buses go almost everywhere else.