First come first served state and national parks

I hear all of your warnings and appreciate them. I will look at our itinerary and maybe shift things around. I had looked at all info on the NP site and planned for late April already, and we are doing Sequoia first, as @enblethen suggested. Our trip is so full with parks in the south US and desert west, It will be OK if we do not end up getting to Yellowstone, but I hope we can at least take some snowshoes in and experience it a bit. Thanks for the advice!