Do not do three themes in one day
Old Quarter lanes, the mausoleum queue and the West Lake loop each take half a day-plus. A first trip plans two main axes — not mausoleum morning + West Lake afternoon + Beer Street night. Xe ôm and walking are different tempos; budget walking time for the Old Quarter last mile.
Split the transit
Walk central districts; Grab/taxi beats forced bus transfers across town. Cat Linh–Ha Dong metro is useful for a south / Literature half-day — not an Old Quarter loop. Noi Bai picks one city end (Hoan Kiem / Ba Dinh / West Lake); do not bolt to Halong on landing day.