Before I went to Vietnam, the only dish that I could associate with Vietnamese cuisine is Pho. It's essentially rice noodle in soup and it can be found pretty easily in Saigon. When we first arrived at Saigon, we didn't know where to dine at but thankfully there was a Pho 24 outlet near our hotel!
Essentially, Pho 24 is a chain of restaurants that specialises in fast-food-like Pho. The service is brisk, the price is reasonably cheap and the quality is pretty average. In short, Pho 24 is a good place to dine at if you've a budget to keep to or if you're extremely hungry and have no time to look for nice restaurants to eat at.
I chose to order their special fruit shake (which I think contains strawberries, honey and I forgot what else) and it was surprisingly good! (: The shake was thick and fruity! A delightful drink to have on a hot day.
Condiments which we could add to our bowls of pho.
Caramel custard. We each had one of this for dessert. It's essentially a custard flavoured pudding and it's not too sweet so it's quite nice. I think my brother will like this though it's definitely not as wobbly as his Hokkaido milk pudding at Sushi Tei.
271 Pham Ngu Lao (it should be quite near your hotel)
Other Pho places that are near your hotel which you may want to try:
Pho Quynh - 323 Pham Ngu Lao (order pho bo kho)
Pho 2000 - 1-3 Phana Chu Trinh (near Ben Thanh Market)