I wish I knew what the changes would be too!!!
So, to upgrade your certificate to a Cat 8, you call into the Marriott Rewards number. Tell them you want to attach your certificate to your reservation. If you're short, they'll tell you you don't have enough points. But you can transfer SPG points to Marriott right then and there (you log into your Starwood account and do the transfer online), it is instant, and then they will upgrade your award to a Cat 8. If you're short on points, you just need to have the points in your Marriott account 10 days prior to check-in, so that's your true deadline: 10 days prior to check-in.**
For my situation, I'm going with the Cat 1-5 travel package redemptions. Once Marriott has its act together and comes out with the hotel category list, I can make decisions. If my Cat 8 hotel is going to cost me more after 8/1 than compared to now, then I'll upgrade that package before 8/1 so that I'm locked in at the current point cost. There are some downsides to my plan though. One of my resort reservations has a 30 day cancellation policy (seems that each hotel sets its own policy on this and while most are the same, there are some oddballs) so I could potentially lose all those points if I don't go to that resort after all. And
travel insurance doesn't reimburse you for FMV of points like it would if you made a cash booking AFAIK.
** ETA: To be more clear, your
hotel reservation needs the points in your account 10 days prior to check in. But you need all the points in your account at that moment to redeem a Cat 1-5 package.