Hmmmm, I can see two possible itineraries, based on your 3-day tickets and an OBB ticket. I am definitely in the camp of “don’t do a park on your party day” based on my past experiences, this past weekend included, but I’m also in the “I don’t want to do a half day on my last day because i love the parks at night“ camp. LOL. So with those disclaimers in mind my suggestion would be the following…
Option 1:
10/30 - DL - prioritize non WDW things
(G+ for Indiana, Haunted Mansion Holiday and other ride of your choice*). Take a nice mid day break and head back around/after dinner and capitalize on your day 1 adrenaline and close down that park! Don‘t wait until your last day to see the fireworks, try and catch them tonight with a view of the castle - you can watch from a different location (Galaxy’s edge, small world) on your next DL day.
10/31- OBB only (arrive between 4:30-6pm)
Sleep in, have lunch at downtown disney. Get ready for OBB but avoid the crush of humanity during mix in time and arrive a bit later. If you arrrive before the party starts head to Guardians and ride it. Then prioritize party only stuff: treat trails - perhaps have your son pick his top 3 Villians (skip the candy only ones but DO NOT MISS Ernesto de la Cruz. He is amazing, we saw him twice he was so good!!), Villians grove (must be dark to experience) and parade if of interest. Don’t “waste” time on rides other than guardians and perhaps Racers (short line/better at night) because you will do them on your DCA day. Maybe hop in line for Incredicoaster right before 11 and close it out that way.
Don’t let the long lines for the treat trails or villains grove fool you, they move fast!
11/1 - DL
No need to rope drop, but try and arrive in the morning to maximize G+. Do anything you didn’t do on day 1, and compare the WDW and DL versions (Big Thunder, Small World, Space, etc.) Mid day break and catch fireworks (if running) from a different location.
11/2 - DCA am
Use G+ for the regular version of Guardians, Webslingers and Incredicoaster. Skip Toy Story, Mermaid, Philharmagic, Soarin (same as WDW). Head to LA as late as possible.
Option 2:
Day 2 - DCA am and OBB
Because it’s a party day, most single ticket guests will go to Disneyland. Zig when they zag. Prioritize rides as in your last day on Option 1, but be sure get a G+ For the Monsters After Dark version of Guardians (they only are available later in the afternoon, so just keep an eye out.) You can use this during the mix in time to save time in line. Then skip rides during the party to do party only things, maybe again hopping on Incredicoaster or Racers just before 11 to end out the night.
* I use G+ like the WDW Fast Pass of yore - use it to secure your top 3 priorities and the rest is a bonus! Be sure to read up on modifying if you aren’t familiar with that from WDW.
HAVE A GREAT TRIP!!!