Firstly, you need to go spend money. Get a hybrid and and a baby seat to put on the back. Then go riding on the Linear track along the Torrens. However, watch out for other cyclists, pedestrians and fallen branches. You want to consider a bike rack to carry the bike instead of throwing it into your car / 4 wheel drive.
The Belair National park is good for starting out and getting used to the bike and the kid on the bike. Balance dynamics can be tricky till you get used to it.
Ive seen some baby seats that go between you/the bike seat and handles...any thoughts on what's better?
BoBike make the seats that sit in front of you. I am starting to see more of them. You can get them through Gazelle Bikes:
Another type is available through a UK company although I'm not sure if they'll ship them for you over here:
Also, Gazelle make a bike called the Bloom that can carry up to 2 children; one in front and one behind:
Thanks for the tips...!
Emily - some good articles in Australian Cyclist magazine
Linear Park obviously is great & lots of spots to stop & let them have a run around if they are getting restless!
Have you already got a baby seat? If not Bike SA has two bikes with babyseats (which you can loan for a day for free) - always good to try before you buy!!
Belair National Park is great - you can ride on all the sealed roads and some of the dirt tracks (if marked they are bike friendly paths) Kuitpo forest could be fun too.