Blizzard Beach will certainly be crowded more on the weekend than during the week given that the locals will be working and attending school during the week. I would go to BB during the week. The two most popular parks on the weekends are MK and MGM. If your staying on grounds, use early entry to go to MK on Sunday morning most of your favorite rides you can knock out first thing in the a.m and have the rest of the day to enjoy a few other rides at MK or transfer in afternoon to MGM. As for Saturday, if you want to be at MGM when it opens you should be able to do ToT and RnRC first thing then make a round about the park. In the evening, I would head on over to Epcot.