Depends on your interests, of course.
I think , not many attractions worth seeing in Saigon.
Best to just walk about the parks in the centre, if you can stand the boiling weather and interact with people or just observe.

Around the cathedral there is such area.
Around the opera house, another.

Fun to sit at coffee shops, including McCafes. 

Walk about along the river there in D 1.

Otherwise, get out of the boiler in the malls, like Takashimaya.

If your not on a small budget, visiting good restaurants gets you sightseeing in the process.

If you're a Bitcoiner, visit Bitcoin Saigon weekly meetup, I think on Thursdays. They are a good expat lot.

#Saigon is a business town. For natural and historic attractions , have to go outside it.
War museum and such, I think are rubbish. 

 Cheers for the info man. Appreciated.