I don't typically do trip reports. But I've done a trip with a 20 month old, and then a 5 year old and a 20 month old, and a 6 year old and a 2.5 year old.
1) Pace yourself and be flexible. My youngest was absolutely done by day 3 or day 4 of our last week long parks trip and my oldest wasn't big into rides.
2) Everyone needs space at the end of the day. It doesn't matter how close you are, the family units will probably need some down time at night apart from each other.
We're not RD to park close people with the kids, mine just can't hang that late and if we tried to push it the next day would be miserable....so if you're trying to do fireworks, maybe do it at the beginning with a lighter day the next day or at the very end of the trip and deal with the cranky on check out day.