"Design a vibrant and captivating promotional image for a group tour to Vietnam. Capture the essence of Vietnam's rich culture, stunning landscapes, and unique experiences. Include iconic elements like traditional ao dai dresses, bustling street markets, lush rice paddies, and serene Halong Bay. Use a color palette that reflects the country's lively atmosphere and incorporate text that highlights key tour details such as destinations, dates, and unique activities. The design should evoke a sense of adventure and cultural immersion, appealing to travelers seeking an unforgettable experience in Vietnam."