I am so sorry for your losses. Truly can not imagine. I completely get the wanting everything to be magic and awesome, etc. that adds another layer, but also adds extra emotion that IMO often make the most memorable visits. I still tear up at parades as well and imagine my late father doing his ridiculously embarrassing goofy dance down Main Street.
On that Dec trip I mentioned, we had one day when it POURED down rain. I mean poured. I had switched our reservations at the front desk (GCH) the day before anticipating this, and managed to snag a Storytellers Brunch. We slept in, had a leisurely brunch and hung out in the hot tub when it was just a light drizzle. I bought Yahtzee and a deck of cards in the gift shop and we hung out in the room, got got chocolate in the lobby, etc. Then we had a great dinner at downtown Disney. It was one of the best days! All that to say: things never going according to plan. Determine your priorities and make those the first things you tackle.
Your mid day break plan is what we do. I try and be headed out of the gates by 1pm latest. Every time I stretch that by “just doing one more thing” I regret it.
One mistake I see many make (myself included) is saving the “must do/priority” thing for your last day (like fireworks or a lightsaber build.) Recipe for disaster. Do those things early on, and then you can experience them again if you like. But nothing can ruin a vacation like missing out on the one thing you love the most (like fireworks) because you wanted to “save it” for the last day.
Also, make sure you read up on G+ and modifying. It will make your trip much more enjoyable and less stressful.
Have a fantastic trip making new memories with your family!!!