The aquatic center is still in use at GA Tech. And Tech also got a lot of new housing from the Olympic Village, and a nice new student center.
The Olympic Stadium turned into Turner Field, which will now be a stadium for GA State University.
I believe the velodrome is still in use, although not totally sure about that.
Basically, Atlanta planned very well for the post-Olympic legacy. And I think we threw a pretty good Olympics, all in all. Yeah, there was lots of advertising, but because of it, the city didn't go into tremendous debt.
Plus our opening ceremonies were the world debut of wacky waving inflatable arms guy, so that's gotta count for something.
I also used the aquatic center a couple times to practice kayaking. The coolest part about that pool was you could lower the floor.
However, it was overwhelmingly a successful Games. It created a lasted economic boom, and much of the construction saw continued use or was repurposed afterward.
Today, Atlanta is not really remembered as a "bad" Olympics (because international sports organizatinos like the IOC and FIFA have become more disgustingly capitalistic than we ever were). We are likewise not really remembered as an "success" story either, frankly because most cultural commentary prefers not to think about southern American cities at all outside the context of sweeping generalizations about racism (1). But quietly, it was an example of a success story for the host city.
(1) Yeah, between the '96 Games and this year's Super Bowl, Atlanta sports fans are a pretty bitter crowd. Don't mind us!