I have been working on these park reservations for 10+ hours yesterday and today. I am not an AP (so this may not do much for those who are), but I wanted to share what finally worked for me in case it can help someone else. I am going for six days. If I booked my park reservations from the first day forward, I could book three days before it showed parks unavailable. If I booked from the last day backward, I could book four days. I wondered what would happen if I changed up the order. So, just a few minutes ago, I tried Day 1,6,2,5,3 and got stuck on Day 4. So then I tried Day 6,1,5,2,4,3 and was successful in booking all six. I have literally tried everything else using many different browsers, etc., and this is the only thing that worked for me. I hope it helps at least one other person. It's only a little after 8:00 am. where I am, but I'm going to go have a drink!!!