I've always told myself that I'll have a more enjoyable race experience if I have a reasonable amount of sleep. So I go to bed early before race days. I've also learned that running a 10K the half is a tremendous way to almost guarantee a much better sleep before the half. I'm essentially tired enough to conquer nerves. I save fireworks for after the half.
On the subject of runDisney multi race events, I think we sometimes forget how different these races are. If you're someone who likes to stop for photos with characters or just in the parks, then that alters the feel of a race. All of the sudden it's not running 48.6 miles in 4 days, but a different running experience on each of those 4 days.
I'd heard mixed reviews on runDisney 5K races. They were either really fun or way too crowded to be worthwhile. I wound up loving my first 5K at Dark Side this year. I enjoyed the lack of time pressure since this wasn't timed. I loved seeing World Showcase early in the morning. I loved seeing the cast members around World Showcase wave their nations flags as they cheered for us. So even though I would again run through Epcot the next 2 days for the First Order Challenge, it was still different.