Okay, but if you're short on time, remember that you'll be back in January. You're fully welcome to join the post-marathon EMH shenanigans at DHS.
We did Slinky without FP+ twice, but we were also there before the park opened both days.
Alien Swirling Saucers was fun, but I don't know that it's a must do. If you've been to
Disneyland, it's pretty much the same as Mater's Junkyard Jamboree, but with aliens and spaceships instead of tractors. I think the lines are usually medium manageable, but since I've never been in TSL when the park was open to all guests, I'm not entirely sure.