"You are going on a cross-country trip. Airplane, bus, or car? (Or something else entirely – bike? Hot air ballon?)
Biking is out. Going up in a hot air balloon is on my wish list but I am not interested in crossing the entire US that way. An airplane is fine for just going from one coast to the other, or visiting 5 – 10 cities. That is not what I would call true cross-country trip. Bus travel would probably be economical but more than a couple days on a bus would not be my idea of fun. If I were crossing Canada I would opt for Via Rail most of the way. I do not think Amtrak matches the Via Rail service. I still would consider Amtrak combined with some car rentals along the way to see some places beyond the rail line. The best over all however would the classic cross-country car trip that many parents took their children on back in the day. I would want a good compatible person to do the driving. I would not want to camp but staying at mid price hotels would be acceptable. Maybe throw in that hot air balloon ride over the Grand Canyon, or in Napa. Now clear my calendar and give me an ample budget for a 3 to 4 month exploration of the USA.