This type of question has been done to death on this forum. Suggest you use the search box top right corner. Then google Phu Quoc, HCMC, Nha Trang, Da Lat, Mui Ne, Danang, Hoi An, Hue, Hanoi, Halong Bay, Sapa & decide which places interest you. Everybody has different interests. There is a plethora of information about these places on the web.
For accommodation reviews refer to tripadvisor, agoda
travelblogs.org may assist as well
Then, if you have a specific question by all means post it. This forum does not take the place of a travel agency.