Forget the reps, they 50-150$ junks, similar to Canal St.
There are a lot of places to dine at (some local some restaurant):
Cuc Gach (southern), Ngu Binh or Mi Tau (best central VN food), Cha Ca La Vong, Ben Thanh Market (day or night for a fun experience), Thien Nam; Bun Rieu Nguyen Canh Chan, Hu Tiu Ca Nam Loi, etc.
In Nha Trang, stay at Sheraton if you prefer an active trip (it's by the shore and close to everywhere). In town, try Nem Nuong, Bo Lac Canh, seafood restaurant by the cliff (I forgot the name..). Visit Sailing Club at night, it's like a beach bar.
If you prefer relax trip, go to the island resort (Vin Pearl or Six Sense-top notch).
Otherwise, visit Da Nang & Hoi An instead.