Re: Need some suggestions for planning a Chicago trip ...
I think it depends on how much you're doing in what amount of time. I would say you only need the general admission pass if it's going to be part of a couple different things you're doing in one day. If you want to make the Shedd the focal point or the only thing you do that day, then getting the full pass would be good.
It's been a few years since I've been to the Shedd, but it's a large place! And they'll get to see a lot regardless.