I agree with Bridee....

I'm in Melbourne, and I've gone to both baby expos for the last two years.
The parenting expo is a waste of time. The only bonus is that there are not many people there, so you can get to check out the (few) stands that are there.

The pregnancy, babies & children expo is HUGE... and worth going... Although there are so many people it's difficult to move around sometime!
I'm lucky that the big expo is on in October (in Melbourne) - just before I give birth!! So I'll be shopping like a madwoman!