Base in the Old Quarter. Do Hanoi on foot plus short rides, start with the Ho Chi Minh complex before the heat, then use the afternoons for museums, cafes, and one hard adventure day outside the city. Book your airport transfer, water puppet tickets, and any overnight or day tour now, because May is hot, rainy, and busy enough that the good seats go first. This plan keeps you moving every day with 2+ adventure experiences, one nature hit daily, and no tourist-trap spending.