sayakubik,
I am almost positive that you can put the full purchase amount of a Play 4 Days pass towards an annual pass, even if you used all the days. They would simply make your season pass expire one year from the first time you used your Play 4 Days pass. As long as you upgrade by June 4th. If anyone knows anything different, please let me know, as I will be upgrading Play 4 Day passes when I go up in a few weeks.