i'm not sure what date you are looking at, but just now when i tried the CX travel planner did give me quite "proper" flights for DEN-SYD...with a connection time of 90 minutes or 4.5 hours...

if they don't show it, maybe probably it just means that there is really no flights that match your schedule on that day ?personally i like the CX one better because it does give me a lot of connection options that i otherwise would not think of...