if it makes any difference with Wilheim, seaword is probably the quietest in terms of music and flashing lights ect and the shows are great.
IMO movieworld is the best for rides for the older ones, thats the one we go to.
The 3 park pass wont get you into dreamworld as the other 3, movie, sea and wet and wild are all owned by warner bros.
Movie world has nic for kids or some such kiddy land that is prob comparable to what dreamworld has and it has all of the cartoon characters.
I recon you should do seaworld, movie and dream are pretty much the same.