Chattahoochee River - Ah, way down yonder by the Chattahoochee… this stretch of river always has water (as of now!) and was formerly the site of the (in)famous shoot-the-hooch summer event.
No particularly great play sites — even at higher water — though the play isn’t any worse at low water: the devil’s racecourse channel opens up at low water with decent squirt and ender spots.
Nancy Creek - Slightly more gradient than the North or South Fork of the Peachtree. Definitely a different view of the city. A fun canoe float at low water and a interesting exploratory run for those with the skills to avoid wood in a flood.