You will need the express pass plus if you go on either Friday or Saturday after Thanksgiving. Sunday will probably not be too crowded though. You can buy the express passes at the ticket booth and at various other places in the park. Also there are express pass machines like the fast pass at Disney that are free but are limited.
This is a plan for 2 days not one. If you decide to do a 2-park one day ticket you will have to revise this. You may also want to hit more kiddy rides since you have an 8 year old. I have teenagers.
If you decide not to buy express passes then get to the park entrance gate by 8:30 AM. They usually open 15-30 minutes earlier than the 9:00 AM posted opening. At Universal Studios, pick up a free express pass for Mummy and then go to Shrek. Then head to the back of the park, ride Men in Black, Back to the Future, and Jaws. Then it should be time for your Mummy fast pass. Ride Mummy and get an express pass for Jimmy Neutron. Then head to Twister and then Earthquake. Next do Terminator. Then it should be time for your express pass for Jimmy Neutron. Get an express for ET and then go to Horror Makeup show. Then catch one of the other shows like Animal Planet Live, Beetlejuice, or Ghostbuster. Then hit ET. Re-ride MIB and the Mummy using the single rider line. I didn't mention lunch in there. I usually grab a bite wherever I am at when I get hungry.
Now for my Islands of Adventure strategy. Once again be at the gate entrance by 8:30. Get an express for Spiderman and then ride Hulk. Then hit Spiderman. You probably won't need to use your express so save it for a second ride later in the day. Head for Jurassic Park, skipping Toon Lagoon for now. Ride JP River Advnenture. Then on to Dueling Dragons and then Poisiden. Then head for Suess Landing, ride Cat in the Hat or anything that interests you there. Now it should be time for your Spiderman express pass. ride it again and head for Toon Lagoon. Either ride Popeyes or Dudley, which ever has the shortest wait time but get an express pass for the one with a longest wait first. Grab a bite to eat and then use your final express pass that you got for either Popeye's or Dudley. Be aware you will get completely drenched on both of those rides so if it is cold you may want to skip them.