The reason we went with two party dates, was an experience from the P&PP. We started out at the HM, (after ressies at the Liberty Tree, getting out just before the offical start of the party), and worked our way slowly counter clockwise, catching the parade from the Hub, and fireworks from just outside Cosmic Rays, our cranky then 3 yr old daughter perked up when she saw Ariel's dance party and any tired/crankyness was forgotten, and she danced, danced, danced (Funny too, she was in a Cinderella Costume, and the "glass slipper shoes was a smidge big on her, and she kept losing her "slipper" as she danced.) My DW was 5 months pregnant with DD#2, so she was content to sit and watch from afar while I stayed close and took pictures and videos. After a long while, she took over watching duties to give me a chance to run to BTMR for a ride, it'd been years since I'd been on it. I made my way through Fantasyland just to where you reach Liberty Square, when I sighted Cinderella's Coach. Ooops! My wife so badly wanted a pic with it, and we'd forgotten it was in the park that night. I ran back and gathered them up to go, but my daughter did NOT want to go and had a little meltdown, which broke my heart.
Thus two party dates...the first is to see everything, parade and fireworks, the sights and trick or treats, maybe a couple of rides if desired. The second we agreed is for my daughters. If they want to party all night, they can, we can swap out and so rides etc. Everyone is happy then