Vietnam

The country that sets the standard for this list. For US passport holders, a 90-day e-visa costs $25 for a single entry, long enough to travel the whole length of the country slowly. Trains and sleeper buses link Hanoi, Hue, Da Nang (the nearest station to Hoi An) and Ho Chi Minh City, family homestays are everywhere, and pho or banh mi from a street stall is a daily pleasure rather than a splurge. The northern mountain loops around Ha Giang and the limestone country near Ninh Binh give a long trip real variety beyond the coast. Apply only through the official government e-visa site, because lookalike agency sites charge several times the fee.