Yep as Pete menioned, if you're in Glenleg you can't go past the Patawalonga river. Great scenery from boats to houses to spoilt little rich girls walking thier chihuahuas

From Glenelg it's 30 mins to the Onkaparinga which is generally only a high tide option in the lower reaches or West Lakes 10 - 15mins North.
If you want anything more than a couple of K's in paddle length, I'd suggest West Lakes where you can view the spoilt little rich girls wealthy grandmothers in their natural tanning environment...their back yard!