Begin your trip with a visit to the War Remnants Museum in the morning. For lunch, head to Bến Thành Market where you'll find a wide array of street foods. Spend the afternoon visiting the Notre-Dame Cathedral Basilica of Saigon and the Central Post Office. End the day with a visit to The View Rooftop Bar for some drinks and a panoramic view of the city.
Start the day with a visit to the Ho Chi Minh Mausoleum Complex and the One Pillar Pagoda. For lunch, try some of Hanoi's famous pho at Pho Gia Truyen. Spend the afternoon at the Temple of Literature and the Hoan Kiem Lake. End the day with a pub crawl in the Old Quarter.
Take a cruise around Ha Long Bay and enjoy the scenic views. Visit the Thien Cung Cave and the Dau Go Cave. Have lunch on the boat and take a swim in the bay. End the day with some nightlife in Tuan Chau Island.
Start the day with a visit to the Japanese Covered Bridge and the Old House of Tan Ky. Have lunch at the Bale Well Restaurant for some local cuisine. Spend the afternoon at the Hoi An Ancient Town and the Assembly Hall of the Cantonese Chinese Congregation. End the day with some drinks at the Q Bar.
Start the day with a visit to the Marble Mountains and the Museum of Cham Sculpture. For lunch, try some seafood at the Be Man Seafood Restaurant. Spend the afternoon at the My Khe Beach and the Son Tra Mountain (Monkey Mountain). End the day with some drinks at the Sky36 Bar.
If you have more time, consider visiting the Mekong Delta or the Cu Chi Tunnels in Ho Chi Minh City. You can also take a day trip to the Ba Na Hills from Da Nang. To maximize your fun, book a Vietnamese cooking class or a motorbike tour. Other suggestions include trying egg coffee, shopping for souvenirs at the night markets, and watching a water puppet show in Hanoi.