I came back from VN about 3 weeks ago. First time there.
Stayed in district 1 in HCM during the first week. Street food readily available everywhere. Ben Thanh market and a dozen other places within walking distance.
After HCM, Danang for almost a week. We rented scooters for a few days ($6 cad/day). We packed minimally and took the scooter to Hoi An and stayed there for one night (I recommend doing this) and came back to Danang.
Been to Thailand a half a dozen times before Vietnam. Honestly, I find Vietnam better.